The Evolution of Modern-Day Dog Training
Today’s dog trainers owe much to their predecessors.
By the 1980s, there was a paradigm shift toward more positive methods in dog training. Only 20 years before, many trainers felt that dogs had to be “broken” in order to be trained. These changes in thinking matched what was happening in the treatment of people with disabilities and mental health problems. In the 1960s, humans were often treated with shock therapy and the use of aversive stimuli. By the 1980s positive behavioral procedures were commonplace in both dog training and human services settings.
Starting in the 1980s, the dog training world seemed to ‘discover’ operant conditioning. The principles of operant conditioning are far from new and this discovery was actually a re-discovery of principles that dog trainers had been using nearly a century ago.
Beginning in the 1800s, without using the technical terminology or being aware of the scientific theories related to training, dog trainers were using many operant conditioning procedures. The early dog trainers played a critical role in developing the world of dog training as we know it today.
After the cavemen brought wolf cubs into their dens as companions, domesticated dogs were used for purposes such as hunting, herding, droving, pulling sleds, and killing vermin. Tibetan Terriers are thought to have been bred and raised by monks in Tibetan monasteries as long as 2000 years ago to serve as pets and assist with the care of flocks and herds. In the 1790s, during her imprisonment, Josephine reportedly used her Pug to carry messages to Napoleon. In the 19th Century, Asian tribes were using sled dogs to carry loads. All of these dogs had some training that was most likely provided by the owners and based on trial-and-error. There were no dog obedience training classes and no manuals or videotapes designed to teach you to teach your dog to carry messages out of your prison cell.
Dogs shows in taverns
Beginning in the late 1700s, in England, informal dog competitions were held in events much like county fairs. By the 1800s, informal dog activities had become popular. Many events were held in local taverns and the townspeople came to cheer on their favorite dogs. A British tavern called The Blue Anchor was the main headquarters for the Toy Dog Club, and a specialty show for Toy Spaniels was held in The Elephant and Castle tavern in 1834.
In 1859, English dog fanciers held the first organized dog show. The show included only Pointers and Setters, showing the interest at the time in dogs who had been trained for sporting activities. Fourteen years later, The Kennel Club (England) held its first official dog show.
As in England, the earliest interest in organized dog training in the United States focused on sporting dogs. In the 1700s, George Washington maintained a kennel of foxhounds at Mt. Vernon and competitions involving pointers, setters, and hounds were popular. In 1884, a growing national interest in pure-bred dogs resulted in the formation of The American Kennel Club. Initially, the primary focus of the AKC was to maintain a stud book and serve as a central governing body for dog shows.
From the mid-1880s until the 1930s, there were no obedience events at AKC dog shows. An idea that was borrowed from other countries, dog training was becoming well known in the United States in the 1920s, even though there were no AKC obedience competitions. Owners could have their dogs boarded and trained by professional trainers. Some owners trained in groups and had local competitions. Training dogs for competition and to earn AKC titles didn’t begin in this country until 1933 when Helene Whitehouse Walker decided to show everyone that her Standard Poodle was far more than just another pretty face.
Helene Whitehouse Walker
Walker was a breeder of Standard Poodles, dogs who were thought of by many at the time as “sissies.” She knew about the behavior tests that were being held in England for working dogs. An effective and persuasive woman, Walker began approaching dog clubs and breeders with her idea of holding competitive obedience tests at dog shows. In 1933, in Mount Kisco, New York, eight dogs competed in America’s first obedience trial. The slogan “Train Your Dog,” became popular across the country and in 1934, North Westchester Kennel Club and Somerset Hills Kennel Club held obedience tests at their confirmation shows. By 1936, the American Kennel Club had developed and was using the “Regulations and Standards for Obedience Test Trials” at licensed obedience events.
On the road again
Inspired by the public’s enthusiastic response to obedience and dog training, in 1937, Walker, her friend Blanche Saunders, and their dogs went on the road in a 21-foot-long trailer to give obedience demonstrations across the country. In 1941, the New England Dog Training Club became the first obedience club to become a member club of the AKC. Dog training had arrived in the United States!
Rin Tin Tin: US Calvary’s most valuable soldier
From the 1920s to the 1950s, Americans of all ages watched with wonder as a German Shepherd entertained and amazed them. Lee Duncan, a World War I soldier, found a shell-shocked puppy in the French trenches. He took the dog home to the states and in 1922, Rin Tin Tin made his debut. Rin Tin Tin was so popular, he was credited for saving Warner Brothers from bankruptcy in the 1920s. Referred to as the “U.S. Calvary’s most valuable soldier,” Rin Tin Tin would make spectacular leaps in raging river rapids, hide under the water from a pursuer, and hold the reins in his mouth to drive a horse and buggy. Rin Tin Tin died at the age of 16 and was buried in Paris. At the time of his death, he was receiving 2000 fan letters every week, showing that people of all ages and backgrounds were fascinated with the idea of a highly trained dog.
Lassie: A 50 year tradition
A 1938 story involving a collie started a tradition that lasted more than 50 years. Joe was a boy whose family had to sell their collie because they could not afford to keep it. The story touched the hearts of so many people it was eventually made into a novel and feature motion picture with Elizabeth Taylor and Roddy McDowall. “Pal,” the original Lassie, made his debut in 1943 in Lassie Come Home. Rudd Weatherwax was Pal’s trainer and eight generations of Lassies later, Rudd’s son Bob was carrying on the tradition of training Lassies using positive training methods. For many people growing up in the 1950s, Sunday nights were the high point of the week. It was then that we could watch a beautiful, well-trained dog who was so devoted she would travel miles and overcome any obstacles to get to her owner. It was the human-animal bond at its finest.
Conrad Most: The beginning of training curriculums
In the early 1900s, Pavlov was in Russia studying reflexive responses in dogs. In their psychology labs, Thorndike was working on the Law of Effect and J.B. Watson was advocating a move toward the scientific, objective study of behavior. At the same time that these researchers were developing the foundations for operant conditioning, dog trainers were making their own contributions toward developing a technology for training. By the 1930s, Walker and Saunders were using an ancient, unair-conditioned Buick to pull a trailer across the country so that people could learn about training their dogs.
In Germany, Colonel Conrad Most was training dogs and explaining their learning tendencies from a dog trainer’s perspective. Most started training police dogs in 1906, and in 1912 he became the director of Berlin’s State Breeding and Training Establishment for police dogs. From 1919-1937 Most headed the Canine Research Department of the Army, and in 1931 he helped form the German Society for Animal Psychology.
In the 1940s, Most used his dog training knowledge to train the handlers and trainers of dogs at the German Dog Farm, a training center for guide dogs and their blind handlers.
Most demonstrated an understanding of operant conditioning concepts such as primary and secondary reinforcement, shaping, fading, and chaining some 28 years before the publication of B.F. Skinner’s The Behavior of Organisms. Most described reinforcement as “that agreeable experience when the dog has performed a correct behavior,” and he differentiated between primary and secondary reinforcers. He referred to secondary reinforcers as “secondary inducements,” and used his voice and soft tones much in the way some trainers use clickers today.
As with many trainers who came from a police or military background, many of Most’s procedures would be regarded as “heavy-handed” by today’s trainers. Nonetheless, it is important to recognize that an early dog trainer had independently discovered many of the relationships between consequences and behavior that Skinner would later describe in The Behavior of Organisms. Most’s 1910 manual Training Dogs was one of the first “how to train” dog books.
Josef Weber
Josef Weber came to the US from Germany, where he was an instructor in the Berlin Police Force. In addition to teaching military and police dogs, Weber had developed procedures for teaching guide dogs for people who were blind. Weber became an American Kennel Club judge and is credited as having a critical role in developing the formal dog obedience tests used in this country. Weber advocated training for all dogs and advised owners that they should “be proud of your dog’s manners.”
William “Bill” Koehler
Like Conrad Most and Josef Weber, Bill Koehler had experience training military dogs. He trained dogs and their handlers at two military training centers in California. Beginning in 1946, Koehler was the chief trainer for the Orange Empire Dog Club. This club was known for its consistently winning performances in team competitions and for large numbers of obedience titles acquired by members. Koehler and his son, Dick Koehler, also trained students at their own training facility. By 1960, more than 40,000 dogs were trained in classes instructed by Koehler or his instructors.
Koehler is credited for starting the use of long lines and light lines in training, methods designed to improve attentiveness and off-leash control. As the head animal trainer for Walt Disney Studios, he introduced millions of Americans to the potential of dog obedience training with his training of Wildfire, a Bull Terrier named the Outstanding Animal Actor in 1955 for his role in It’s a Dog’s Life. This prestigious award was given to another Koehler-trained dog in 1959 when “Chiffon,” better known to most of us as The Shaggy Dog, was voted the best animal actor.
The Koehler method of training is based largely on the principles of negative reinforcement and punishment. In operant conditioning, negative reinforcement occurs when the frequency of a response increases if an aversive event is removed immediately after the response has been performed. This means, if the dog starts doing what you wanted him to after you did something aversive, he was getting negative reinforcement from escaping or avoiding the aversive stimulus.
One of the most frequently used examples of negative reinforcement in dog training is the use of the “choke chain” or chain training collar. After experiencing unpleasant jerks on the chain, many dogs work hard to avoid the jerk. Koehler used choke chains in procedures such as turning quickly and going in the opposite direction of the dog when the dog was forging ahead or pulling the handler.
An example of punishment in the Koehler method is the use of “throw chains.” Koehler used throw chains to control the dog from a distance. For example, if the dog was called and did not respond, the chain would be thrown sharply at the dog’s rear. According to Koehler, as the chain hits the dog, the handler is to reel in the leash and have the dog sit front. When the dog is positioned in front, Koehler instructs handlers to provide lavish praise, showing that he believes in reinforcing dogs for what they have done correctly.
In training, Koehler advocated letting dogs make mistakes, providing consequences for those mistakes, and then providing praise for desired behavior. In cases where dogs had behavior problems such as digging, jumping on people, and barking, Koehler believed in the use of punishment. Punishment, in the operant conditioning, scientific context, is defined as providing a consequence that makes a particular behavior less likely to occur in the future.
Times have changed since Koehler started training dogs. While he stood by his techniques throughout his life, Koehler’s punishment procedures are not considered necessary, humane, or appropriate by many of today’s trainers. For dogs who were diggers, Koehler advised digging a hole, filling it with water, and putting the dog’s nose into the water. According to the Koehler methods, dogs who jump on people should receive a sharp knee in the chest, and dogs who bark excessively should be hit with a leather belt.
The paradigm shift in dog training seems to match changes that have occurred over the years in treating people with disabilities and mental health problems. In the 1960’s, patients in institutions were treated with shock therapy and aversive stimuli such as lemon juice and ammonia were routinely used with behavior-problem patients. It was believed then that punishment was the fastest, most effective way to fix a severe behavior problem. With the exception of a few unusual cases in highly specialized treatment facilities, these procedures are not used today and would be considered abusive. Like human therapies, for the most part, dog training has undergone an evolution and moved toward a more positive approach.
I met Bill Koehler and watched him work with dogs and students in the 1980’s. He appeared then to be a kind and gentle man and he clearly loved dogs. At the time Koehler developed his procedures, he was one of the few people in the country who was known for his ability to rehabilitate tough dogs. For many dogs, Koehler was the last hope. If he couldn’t “fix” them in a short period of time, they would be put to death. While the trend in the 1980s and 1990s has been toward positive approaches to dog training, and many of Koehler’s procedures are criticized, Bill Koehler can not be denied recognition for the major impact he had on dog training in this country. His 1962 book The Koehler Method of Dog Training is an obedience classic that has lasted nearly a half a century and has been used to train hundreds of thousands of dogs.
Blanche Saunders
After Blanche Saunders’ and Mrs. Helene Whitehouse Walker’s incredible cross-country journey to sell the benefits of dog training to the American public, Saunders continued to promote the newly emerging sport with missionary zeal. She organized obedience demonstrations at high visibility events such as the Westminster Dog Show, in Rockefeller Center during National Dog Week, and during intermissions in Yankee Stadium with 70,000 spectators.
In 1954, Saunders published her book, The Complete Book of Dog Obedience. This was the first book written specifically for obedience instructors and in it, Saunders outlined the format for procedures that would be adopted in dog training classes across the country.
Saunders showed an understanding of the principles of learning. She said, “Dogs learn by associating their act with a pleasing or displeasing result. They must be disciplined when they do wrong, but they must also be rewarded when they do right.” Saunders advocated the use of punishment procedures for some behavior problems. When dogs barked in class, owners were instructed to hold the muzzles and tell the dog to behave. If the dog continued to bark, Saunders wrote that the owner should hold the leash tight and the dog should be “cuffed sharply across the end of the nose.”
Negative reinforcement procedures played a key part in Saunders’ method. Perhaps the most frequently used negative reinforcement procedure (where the dog attempts to avoid something aversive) is the jerking of the choke chain. When a dog receives a jerk by the chain collar, the procedure is technically considered punishment. However, when the dog hears the “click, click, click,” of the chain collar as the trainer prepares for a correction and works to avoid the correction, the procedure is negative reinforcement.
In the Saunders method, to teach heeling, the instructor tells the handlers, “Forward.” Students are instructed to say, “Heel! Jerk! Praise!” Jerks are also used to both teach behaviors such as sit and down and to correct problems such as inattentiveness.
Food training was virtually unknown when Saunders was training dogs. Saunders felt that food should not be given “like a bribe” on an on-going basis, but that it was acceptable to use “a tidbit now and then to overcome a problem.” This was perhaps the beginning of the shift away from military and police training methods that relied primarily on punishment, escape, and avoidance behaviors. These methods specifically stated that trainers should never use food in training. Saunders primarily used pats and praise as reinforcers. To teach new skills, Saunders often used physical prompts. Dogs were taught to “down” by having the handler step on the shortened leash. In teaching dogs to “sit,” handlers would apply pressure to the dog’s shoulder to guide the dog into position.
Blanche Saunders made some major contributions to dog training. She was one of the first trainers of obedience instructors and she was an early seminar leader. Her book outlined a curriculum of carefully detailed week-by-week instruction for novice through advanced dog obedience classes. Throughout The Complete Book of Dog Obedience, Saunders set the tone for praising, kindness, and fairness. She listed “too little praise” as one of the most commonly made mistakes of owners. Saunders was perhaps the first author to repeatedly stress the importance of reinforcement in training, thus starting the trend toward the positive training methods used today.
Milo Pearsall
Milo Pearsall’s 1958 book Dog Obedience Training has been billed as a book that revolutionized dog training with a more gentle approach. Many of Pearsall’s training methods were the same negative reinforcement techniques described four years earlier by Blanche Saunders. Pearsall used snapping on the leash as a correction in teaching heeling, to get the dog to sit, and to improve attentiveness.
Pearsall also used punishment procedures for correcting problem behaviors. To correct dogs who jump on people, Pearsall suggested the person knee the dog in the chest. To stop car chasing, owners were told to tie a stick to a short length of rope hanging from the dog’s collar. As the dog ran to chase, the stick hit against the dog’s front legs. For housebreaking accidents, Pearsall suggested that owners push their dog’s noses near the accident (not in it) so that the dog could get the idea of what it had done wrong. In the Pearsall method, dogs who ran away were trained on a line. When they tried to bolt with the long line attached to their collars, they were jerked off their feet.
In 1958, aware of Pavlov’s research on conditioning that had been completed only a few decades earlier, Pearsall wrote, “The dog at first learns his lessons by the application of a primary stimulus – forcing him to sit, for example – and at the same time a secondary stimulus, the command is given to him. Soon, the secondary means exactly the same to him as the primary did. The best-known example of this primary-secondary transfer is the famous experiment of Pavlov on the salivation of dogs.” Unfortunately, while Pearsall knew that there was a connection between learning theory and dog training, he confused the concepts of respondent (reflex) conditioning with operant conditioning (learning). A dog learning when a physical prompt of forcing him into a sit has been paired with the verbal cue, “sit,” is clearly a case of operant conditioning.
Dogs are amazing creatures and they often learn despite confusing messages that we might send. For serious infractions, Pearsall said the dog should be struck under the chin (with the fingers). As soon as the dog was hit for misbehavior, he instructed the handler to then praise the dog immediately.
Behaviorally, we now know that it would not make sense to give a reinforcer immediately after a punisher. Such a pairing would clearly cause the punisher to take on reinforcing qualities.
According to sound behavioral principles, the reinforcer (praise) would not be given until the dog had engaged in an acceptable behavior. Then, that behavior would be reinforced. Pearsall justified the practice of praise as soon as you punish by saying the handler needed to “let the dog know he was still loved” and that the handler was on the dog’s side.
In operant conditioning, the word “punishment” is a technical scientific term that means to provide a consequence that makes a particular behavior less likely to occur in the future. For example, if you grabbed the handle to a new pan that you were cooking with and you were severely burned, in operant terms, you were punished for grabbing the handle of this pan while cooking. Many dog trainers, from years past through the present time, think of “punishment” as having a different meaning. They equate it with a crime, retribution, or a person who is just trying to get even.
Pearsall, like many trainers, did not use the operant conditioning definition of punishment. He believed that as a first rule of obedience training, trainers should “keep also in mind that the dog is never punished. He is corrected. He does not, and never will, understand punishment.” Pearsall used the “crime” version of punishment, here, a distinction wholly lost on the dog.
Dog Obedience Training was a work that was very complete. It included information on selecting puppies, pre-training, and crate training in addition to providing general training information for all levels of instruction. Pearsall was a well-respected AKC obedience judge and instructor. Hundreds of thousands of dogs were trained with Pearsall’s training methods. Pearsall was an early supporter of “kindergarten puppy classes.” These classes for puppies were designed primarily to educate owners and promote socialization among the puppies. Pearsall stressed that these classes should be fun and they should not be formal training sessions that would deny puppies the right to act like playful, joyful, exploring puppies.
Milo Pearsall was perhaps best known for the nationwide seminars and clinics that he conducted to promote dog training and his ability to demonstrate using problem dogs (from the audience) how quickly dogs learn in the hands of a skilled trainer.
Winifred Strickland
Winifred Strickland began competing in dog obedience in the early 1940s. She retired from competition in 1955, just about the time that Blanche Saunders and Milo Pearsall were influencing trainers with their seminars. Strickland, an AKC obedience judge, was one of the earliest “super trainers.” She earned 160 obedience titles, 40 perfect scores, 30 utility titles, three obedience trial championships, five national obedience championships, five tracking titles, plus hundreds of high awards.
In her 1965 book Expert Obedience Training for Dogs, Strickland outlined a sequenced curriculum for novice through utility training. She said that her method would produce dogs that were eager to work.
Strickland used snap-release corrections to teach heeling and to “teach the dog to behave.” If dogs refused commands, she would give them a sharp tap on the nose. For dogs who jumped on people, she used the commonly used procedure of a knee in the dog’s chest. In housebreaking dogs, she used verbal reprimands for when the dog had an accident, and she praised the dog when it eliminated outside. When Strickland had to correct the dog, she believed that punishment should always be administered immediately and the lesson continued so the dog could do something right and get praised. Strickland emphasized the importance of good timing when delivering both punishment and praise.
To teach “down,” Strickland used physical prompts. She pulled the dog’s front legs out as she dropped it into a down position and said, “down, good down.” To drop the dog into a down at a distance, Strickland systematically faded her control of the dog by starting the training with the dog a short distance away and gradually increasing the distance.
Strickland taught her young dogs to do tricks using food as an incentive. She described how she would pair food with praise and eventually the dogs worked for praise alone (conditioned reinforcement). Like most of the other trainers of her times, Strickland advised against using food in training. She said that the use of food “is a crude approach to training and will work only with dogs that think more of their own stomachs than of their owners.” Despite this comment, in Expert Obedience Training for Dogs, Strickland described how food could be used to teach advanced skills such as the “go-out” exercise for obedience. This exercise involves the dog being sent away from the handler, instructed to sit, and then jump over a specified jump. Strickland would place small bits of food at the location to which the dog was directed. The dog would run out to get the food and Strickland would give a verbal signal to have the dog sit. Eventually, the food would be faded from the training and the dog would run out to the location when given a verbal command.
In the 1960’s, a number of leading trainers believed that dogs trained for formal obedience competition should live in kennels. The thinking was that the dogs would be so happy to have human contact they would work eagerly. Strickland disagreed with kenneling dogs. She felt that dogs should live in the home “as family members.” She cited numerous examples of how her German Shepherds practiced their training throughout the day by retrieving items and performing other functional tasks.
Praise was an “integral part” of Strickland’s training method and she advised trainers to “continually strive to instill a feeling of fun in your training to keep your dog enthusiastic.” Winifred Strickland was responsible for a dramatic advance in the movement toward the kinder, more humane training of dogs. Strickland’s comment, “Do not be embarrassed if someone overhears you praising your dog. Be proud of it,” shows us just how far dog training has come in the last 30 years.
Modern Day Influences
Ian Dunbar: Positive training for families
Dr. Ian Dunbar, a veterinarian, is perhaps best known for his work as an animal behaviorist, teacher, lecturer, and innovative promoter of dog training. After receiving his veterinary degree from the Royal Veterinary College in London, Dunbar completed a doctorate in animal behavior at the University of California.
The host of the British television series Dogs with Dunbar, California resident Dunbar has written numerous books and videos. In the 1980s, Dunbar produced the “Sirius” (the dog constellation) puppy training book and video. In a time when the emphasis in dog training was largely on training for formal obedience competition, Dunbar began stressing the importance of training pet dogs. His educational materials and seminars made a significant contribution to dog training by advancing the idea that the dog’s entire family could be taught to shape their dog’s behavior. Dunbar wisely recognized when he was working with families that most people do not like to use aversive corrections with their dogs. He developed a positive, motivational training method that unskilled owners could both learn to use effectively and feel good about the method they were using to train their dog.
By the time Dunbar arrived on the dog training scene, a number of trainers were beginning to promote a more positive approach to training dogs. Dunbar demonstrated in seminars and on videotapes how dogs could be taught new skills very quickly if food “lures” were used during training. Like trainers as early as Milo Pearsall, Dunbar stressed the importance of getting puppies off to a good start. He encouraged trainers to organize “puppy parties.” These parties were designed to socialize puppies, screen potential behavior problems, and get owners involved in the educational loop early in the process.
In 1994, Dunbar’s influence on the dog training world expanded exponentially when he played a key role in founding the Association of Pet Dog Trainers. APDT’s first conference in Orlando, Florida, that year drew 250 professional dog trainers who were interested in issues related to training pet dogs. By 1997, attendance at annual conferences was more than 1000 trainers each year. The 1997 conference program, in addition to a wide variety of other topics, included a number of presentations related to operant conditioning. Speakers talked about punishment, how to use and time reinforcers, stimulus control, and behavior modification techniques, showing that many dog trainers had an interest in the science of how dogs learn.
Karen Pryor
Karen Pryor is a scientist, writer, animal trainer, and seminar leader. For dog trainers in the 1980s and 1990s, Pryor also fulfilled an important role as a translator of basic behavioral concepts for those working in the animal training area. Prior to the 1980s, Pryor was a marine mammal trainer who used Skinner’s operant conditioning principles to teach dolphins and develop marine mammal shows. In 1984, she published her book Don’t Shoot the Dog, a user-friendly, popular press explanation of operant procedures for the general public. In Don’t Shoot the Dog, Pryor used real world situations to explain how operant procedures can be used to change the behavior of one’s children, spouse, roommate, or pets.
When Reader’s Digest, with its readership of more than 20 million readers, published an excerpt of Don’t Shoot the Dog, many behavior analysts were ecstatic that someone had successfully introduced operant conditioning to the general public. In the late 1980s Pryor gave the keynote address to behavioral scientists at the Association for Behavior Analysis International conference and the bridge between science and modern day dog training was established.
Pryor’s training materials and seminars showed how operant procedures can be used to provide training that is positive. Pryor also introduced trainers to concepts such as secondary reinforcement with her “shaping game” and examples of “clicker training.”
By the mid-1990s, there were several dog trainers writing and conducting national seminars on how to use clickers in training. Numerous dog trainers were giving workshops and writing on operant conditioning topics such as positive reinforcement, shaping behaviors, and decreasing undesirable behaviors. The long-term impact of these trainers on the field of dog training is not yet known.
Understanding the Whole Dog
In the years before operant conditioning was a term familiar to dog trainers, well-known trainers introduced new training methods or modifications of old ones with a steady regularity. However, despite a consistently growing number of books and seminars on “how to train,” leading trainers have understood for decades that more is required to train a dog than a set of procedures or bag of tricks.
The field of dog training has changed dramatically in recent years and the overall trend has been toward an increased use of positive reinforcement. While strategies have changed, some of the characteristics of good trainers have remained constant. Good trainers understand the whole dog. Although we can make some generalizations about learning theory and what happens when an animal is reinforced or punished, we cannot deny the role that genetics and breed or species differences play when we are trying to change an animal’s behavior.
How Dogs Learn by Mary R. Burch and Jon S. Bailey can be ordered through Amazon.
This article was reprinted by permission.