Hallucinogens and Hallucinogen-Related Disorders

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Editor: Deirdre S. Blanchfield
Date: 2016
Publisher: Gale, a Cengage Company
Document Type: Drug overview
Length: 3,908 words

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Hallucinogens and Hallucinogen-Related Disorders


Hallucinogens are a chemically diverse group of drugs that cause changes in a person's thought processes, perceptions of the physical world, and sense of time. Hallucinogens are found naturally in some plants and can be synthesized in the laboratory. Most hallucinogens are abused as recreational drugs. Hallucinogens are also called psychedelic drugs.


Hallucinogens, or psychedelics, are substances that alter users' thought processes or moods to the extent that they perceive objects or experience sensations that have no basis in reality. Many natural and some synthetic substances have the ability to bring about hallucinations. Due to a ready market for such chemicals, they are manufactured in illegal laboratories for sale as hallucinogens. LSD (lysergic acid diethylamide) and many socalled designer drugs have no useful clinical function.

The use of hallucinogens is at least as old as civilization. Many cultures have recorded eating certain plants specifically to induce visions or alter the perception of reality. Often, these hallucinations were part of a religious or prophetic experience. Shamans in Siberia were known to eat the hallucinogenic mushroomAmanita muscaria. The ancient Greeks and the Vikings also used naturally occurring plant hallucinogens. Peyote, a spineless cactus native to the southwestern United States and Mexico, was used by native peoples, including the Aztecs, to produce visions.

Although several hundred plants are known to contain compounds that cause hallucinations, most hallucinogens are synthesized in illegal laboratories for delivery as street drugs. The best-known hallucinogens are lysergic acid diethylamide (LSD), mescaline, psilocybin, and MDMA (ecstasy). Phencyclidine (PCP, angel dust) can produce hallucinations, as can amphetamines and marijuana, but these drugs are considered dissociative drugs rather than hallucinogens, and act by a different pathway from classic hallucinogens. Dextromethorphan, the main ingredient in many cough medicines, has become popular among some populations because of the PCP-like hallucinations it produces. In addition, new designer drugs that are chemical variants of classic hallucinogens are apt to appear on the street at any time. A drug that only recently was added to Schedule I of the 1970 Controlled Substances Act (the classification for many other “hard” drugs with no known therapeutic value) is 5-methoxy-N, N-diisopropyltryptamine (5MeO-DIPT), a drug derived from the chemical tryptamine, which is more commonly known as Foxy or Foxy Methoxy. A related hallucinogen, dimethyltryptamine, occurs naturally in plants in the Amazon but is now synthesized in labs. This drug, more commonly known as DMT, can be a powerful hallucinogen.

Although the various hallucinogens produce similar physical and psychological effects, they are a diverse group of compounds. However, all hallucinogens appear to affect the brain in similar ways. While the mechanism of action of hallucinogens is not completely understood, research has shown that these drugs bind with one type of serotonin receptor (5-HT2) in the brain.

Serotonin is a neurotransmitter that facilitates transmission of nerve impulses in the brain and is associated with feelings of well-being, as well as many physiological responses. When a hallucinogenic compound binds with serotonin receptors, serotonin is blocked from those receptor sites, and nerve transmission is altered. There is Page 1190  |  Top of Articlean increase in free (unbound) serotonin in the brain. The result is a distortion of the senses of sight, sound, and touch; disorientation in time and space; and alterations of mood. In the case of hallucinogen intoxication, however, a person is not normally delirious, unconscious, or dissociated. He or she is aware that these changes in perception are caused by the hallucinogen.

Percentage of high school students who ever used hallucinogenic drugs,* by sex, race/ethnicity, and grade, 2014

Percentage of high school students who ever used hallucinogenic drugs,* by sex, race/ethnicity, and grade, 2014
SOURCE: Centers for Disease Control and Prevention (CDC). Youth Risk Behavior Surveillance—United States, 2013. MMWR 2014; 63(No. SS-4): 102.


LSD was first synthesized in 1938 by Dr. Albert Hofmann, a Swiss chemist who was seeking a headache remedy. Years later, he accidentally ingested a small, unknown quantity, and shortly afterward he was forced to stop his work and go home. Hofmann lay in a darkened room and later recorded in his diary that he was in a dazed condition and experienced “an uninterrupted stream of fantastic images of extraordinary plasticity and vividness … accompanied by an intense kaleidoscope-like play of colors.”

Three days later, Hofmann purposely took another dose of LSD to verify that his previous experience resulted from the drug. He ingested what he thought was a small dose (250 micrograms), but which is actually about five times the amount needed to induce pronounced hallucinations in an adult male. His second hallucinatory experience was even more intense, and his journal describes the symptoms of LSD toxicity: a metallic taste, difficulty in breathing, dry and constricted throat, cramps, paralysis, and visual disturbances.

Pure LSD is a white, odorless, crystalline powder that dissolves easily in water, although contaminants can cause it to range in color from yellow to dark brown. LSD was listed as a Schedule I drug under the Controlled Substance Act of 1970, meaning that it has no medical or legal uses and has a high potential for abuse. LSD is not easy to manufacture in a home laboratory, and some of its ingredients are controlled substances that are difficult to obtain. However, LSD is very potent, and a small amount can produce a large number of doses.

On the street, LSD is sold in several forms. Microdots are tiny pills smaller than a pinhead. Windowpane is liquid LSD applied to thin squares of gelatin. Liquid LSD can also be sprayed on sugar cubes. The most common street form of the drug is liquid LSD sprayed onto blotter paper and dried. The paper, often printed with colorful or psychedelic pictures, is divided into tiny squares, each square being one dose. Liquid LSD can also be sprayed on the back of a postage stamp and licked off. Street names for the drug include acid, yellow sunshine, windowpane, cid, doses, trips, and boomers.

LSD is one of the most potent hallucinogens known, and no therapeutic benefits have been discovered. The usual dose for an adult is 50–100 micrograms. (A microgram is one-millionth of a gram.) Higher doses will produce more intense effects and lower doses will produce milder effects. The so-called “acid trip” can be induced by swallowing the drug, smoking it (usually with marijuana), injecting it, or rubbing it on the skin. Taken by mouth, the drug will take about 30–60 minutes to have any effect and will last around 2–4 hours.

The physiological effects of LSD include blurred vision, dilation of the pupils, muscle weakness and twitching, and an increase in heart rate, blood pressure, and body temperature. The user may also salivate excessively and shed tears, and the hair on the back of his arms may stand erect. Pregnant women who use LSD or other hallucinogens may have a miscarriage, because these drugs cause the muscles of the uterus to contract. Such a reaction in pregnancy would expel the fetus.

To the observer, the user usually will appear quiet and introspective. Most of the time, the user will be unwilling or unable to interact with others, carry on a conversation, or engage in intimacies. At times even moderate doses of LSD will have profoundly disturbing effects on an individual. Although the physiological effects will seem uniform, the psychological impact of the drug can be terrifying. The distortions in reality, exaggeration of perception and other effects can be frightening, especially if the user is unaware that he or she has taken the drug. This constitutes what is called the “bad trip.”

Among the psychological effects reported by LSD users is depersonalization—an out-of-body experience in which the separated mind is observing the passing scene. A confused body image (users cannot tell where their Page 1191  |  Top of Articleown bodies end and the surroundings begin) also is common. A distorted perception of reality often occurs. For example, the user's perception of colors, distance, shapes, and sizes is inconsistent and unreliable. In addition, the user may perceive absent objects and forms without substance. The user may also taste colors or smell sounds, a mixing of the senses called synesthesia. Sounds, colors, and taste are all greatly enhanced, though they may constitute an unrealistic and constantly changing tableau.

Past-year use of hallucinogenic and dissociative drugs among 12th-grade students

Past-year use of hallucinogenic and dissociative drugs among 12th-grade students
SOURCE: National Institute on Drug Abuse. “Hallucinogens and Dissociative Drugs.” Research Report Series. Available online at: http://www.drugabuse.gov/publications/research-reports/hallucinogensdissociative-drugs/why-do-people-take-hallucinogens (accessed July 31, 2015).

The user often talks nonstop on a variety of subjects, often uttering meaningless phrases. But the user may also become silent and immobile for long periods of time while listening to music or contemplating a random object. Mood swings are frequent, alternating suddenly between total euphoria and complete despair.

Some users exhibit symptoms of paranoia. They become suspicious of people around them and tend to withdraw from others. Feelings of anxiety can also surface when users are removed from quiet environments and exposed to everyday stimuli. Activities such as standing in line with other people or walking along a city sidewalk may seem impossible. Users have been known to jump off buildings or walk in front of moving trucks.

How LSD and other hallucinogens produce these bizarre effects remains unknown. The drug attaches to certain chemical binding sites widely spread through the brain, but what ensues thereafter has yet to be described. A person who takes LSD steadily with the doses close together can develop a tolerance to the drug. That is, the amount of drug that once produced a pronounced “high” is no longer effective. A larger dose is required to achieve the same effect. However, if the individual keeps increasing the drug intake, he or she will soon pass over the threshold into the area of toxicity.

Discontinuing LSD or other hallucinogens, especially after having used them for an extended period of time, is not easy. The residual effects of the drugs produce toxic symptoms and flashbacks, which are similar to an LSD trip.

Teens often experiment with LSD or other hallucinogens in reaction to poor family relationships and psychological problems. Others are prompted by curiosity, peer pressure, or the desire to escape from feelings of isolation or despair. Typical physical signs of hallucinogen use include rapid breathing, muscle twitching, chills and shaking, upset stomach, enlarged pupils, confusion, and poor coordination.


Mescaline is a naturally occurring plant hallucinogen. Its primary source is the cactus Lophophora williamsii. This cactus is native to the southwestern United States and Mexico. The plant is blue-green in color, spineless, and features a crown called a peyote button. This button contains mescaline that can be eaten or made into a bitter tea. Mescaline is also the active ingredient of at least ten other cacti of the genus Trichocereus, which are native to parts of South America.

Page 1192  |  Top of Article

Mescaline was first isolated in 1897 by the German chemist Arthur Hefftner and first synthesized in the laboratory in 1919. Some experiments were done with the drug to determine if it was medically useful, but no medical uses were found. However, peyote is culturally significant. It has been used for centuries as part of religious celebrations and vision quests of Native Americans. The Native American Church, which fuses elements of Christianity with indigenous practices, has long used peyote as part of its religious practices.

In 1970, mescaline was listed as a Schedule I drug under the Controlled Substances Act. However, that same year, the state of Texas legalized peyote for use in Native American religious ceremonies. In 1995, a federal law was passed making peyote legal only for this use in all 50 states.


Psilocybin is the active ingredient in what are known on the street as magic mushrooms, shrooms, mushies, or Mexican mushrooms. There are several species of mushrooms that contain psilocybin, including Psilocybe mexicana, P. muscorumi, and Stropharia cubensis. These mushrooms grow in most moderate, moist climates.

Psilocybin-containing mushrooms are usually cooked and eaten, or dried and boiled to make a bitter tea. Although psilocybin can be made synthetically in the laboratory, there is no street market for synthetic psilocybin, and virtually all the drug comes from cultivated mushrooms. In the United States, it is legal to possess psilocybin-containing mushrooms, but it is illegal to traffic in them; and psilocybin and psilocin (another psychoactive drug found in small quantities in these mushrooms) are both Schedule I drugs.


MDMA, short for 3,4-methylenedioxymethamphetamine, and better known as ecstasy, XTC, E, X, or Adam, has become an increasingly popular club drug since the 1980s. The hallucinogenically active portion of the drug is chemically similar to mescaline, while its stimulant portion is similar to methamphetamine. MDMA was first synthesized in 1912 by a German pharmaceutical company looking for a new compound that would stop bleeding. The company patented the drug, but marketed it. A closely related drug, methylenedioxyamphetamine (MDA), was tested by a pharmaceutical company as an appetite suppressant in the 1950s, but its use was discontinued when it was discovered to have hallucinogenic properties. In the 1960s, MDA was a popular drug of abuse in some large cities such as San Francisco.

During the early 1980s, therapists experimented with MDMA, which was legal at the time, as a way to help patients open up and become more empathetic. Recreational use soon followed, and it was declared an illegal Schedule I drug in 1985. For about a year between 1987 and 1988, the drug was again legal as the result of court challenges, but it permanently joined other Schedule I hallucinogens in March 1988.

MDMA is a popular club drug often associated with all-night raves or dance parties. The drug, sold in tablets, is attractive because it combines stimulant effects that allow users to dance for hours with a feeling of empathy, reduced anxiety, reduced inhibitions, and euphoria. Some authorities consider MDA and MDMA stimulant-hallucinogens and do not group them with classic hallucinogens such as LSD, but research indicates that MDA and MDMA affect the brain in the same way as classic hallucinogens. The American Psychiatric Association considers MDMA a drug that can cause hallucinogenrelated disorders.

Causes and symptoms

Hallucinogens are attractive to recreational drug users for a number of reasons, including the following:

  • They are minimally addictive, with no physical withdrawal symptoms upon stopping use.
  • They produce few serious or debilitating physical side effects.
  • They do not usually produce a delusional state, excessive stupor, or excessive stimulation.
  • They do not cause memory loss with occasional use.
  • They are easily and cheaply available.
  • They produce a high that gives the illusion of greater creativity, empathy, or self-awareness.
  • They rarely lead to overdose or death.

Despite their perceived harmlessness, strong hallucinogens can cause frightening and anxiety-evoking emotional experiences, known as bad trips. Flashbacks, where the sensations experienced while under the influence of a drug recur uncontrollably without drug use, can occur for months after a single drug use. During hallucinogen intoxication, reality may be so altered that users may endanger themselves by believing they are capable of such feats as flying off buildings. Hallucinogens also may induce or cause a worsening of latent psychiatric disorders such as anxiety, depression, and psychosis. Hallucinogens can also cause paranoia, long-term memory loss, personality changes (especially if there is a latent psychiatric disorder), and psychological drug dependence.

Page 1193  |  Top of Article Psychological symptoms

Hallucinogens work primarily on the perception of reality. They usually do not create true hallucinations, which are imagined visions or sounds (voices heard in the head, for example) in the absence of any corresponding reality. Instead, classic hallucinogens alter the perception of something that is physically present. A face may appear to “melt” or colors may become brighter, move, and change shape. Sounds may be “seen,” rather than heard.

More than with other drugs, the mental state of the hallucinogen user and the environment in which the drug is taken influence the user's experience. LSD, especially, is known for symptoms that range from mellowness and psychedelic visions (good trips) to anxiety and panic attacks (bad trips). Previous good experiences with a drug do not guarantee continued good experiences. People with a history of psychiatric disorders are more likely to experience harmful reactions, as are those who are given the drug without their knowledge.

Normally, mescaline and psilocybin produce uniformly milder symptoms than LSD. During a single drug experience, the user can experience a range of symptoms. Mood can shift from happy to sad or pleasant to frightening and back again several times. Some symptoms occur primarily with MDMA, as indicated. Psychological symptoms of hallucinogen intoxication include the following:

  • distortion of sight, sound, and touch
  • confusion of the senses—sounds are “seen” or vision is “heard”
  • disorientation in time and space
  • delusions of physical invulnerability (especially with LSD)
  • paranoia
  • unreliable judgment and increased risk taking
  • anxiety attacks
  • flashbacks after the drug has been cleared from the body
  • blissful calm or mellowness
  • reduced inhibitions
  • increased empathy (MDMA)
  • elation or euphoria
  • impaired concentration and motivation
  • long-term memory loss
  • personality changes, especially if there is a latent psychiatric disorder
  • psychological drug dependence.
Physical symptoms

Although the primary effects of hallucinogens are on perceptions, some physical effects do occur. Physical symptoms include the following:

  • increased blood pressure
  • increased heart rate
  • nausea and vomiting (especially with psilocybin and mescaline)
  • blurred vision that can last after the drug has worn off
  • poor coordination
  • enlarged pupils
  • sweating
  • diarrhea (plant hallucinogens)
  • restlessness
  • muscle cramping (especially clenched jaws with MDMA)
  • dehydration (MDMA)
  • serious increase in body temperature leading to seizures (MDMA).


Hallucinogen use, excluding MDMA, peaked in the United States in the late 1960s as part of the counterculture movement. Hallucinogen use then gradually declined until the early 1990s, when it again picked up. A recent government survey found that about 33.7 million Americans (13.9%) age 12 or older report having tried a hallucinogen at least once in their lives. About 22.4 million Americans (9.2% of the population) age 12 or older report having used LSD at least once, with 104,000 reporting use within the last month. Among teenagers, use of these drugs has remained fairly stable with some declines in recent years.

A recent U.S. government survey found that about 11.5 million Americans age 12 or older report having tried MDMA at least once. About 0.2% of the population reported having used the drug in the last month. Among adolescents, use of the drug appears to have increased in recent years. A total of 6.5% of twelfth graders reported having tried MDMA in the past month according to a recent survey.


Although not all experts agree, two hallucinogenrelated disorders are recognized: hallucinogen dependence and hallucinogen abuse.

Hallucinogen dependence is the continued use of hallucinogens even when the substances cause the affected individual significant problems, or when the Page 1194  |  Top of Articleindividual knows of adverse effects (memory impairment while intoxicated, anxiety attacks, flashbacks), but continues to use the substances anyway. “Craving” hallucinogens after not using them for a period of time has been reported.

Hallucinogen abuse is the repeated use of hallucinogens even after they have caused users impairment that undermines their ability to fulfill obligations at work, school, or home. However, use is generally not as frequent as it is among dependent users.

In addition to these two disorders, the American Psychiatric Association (APA) recognizes eight other hallucinogen-induced disorders, namely:

  • hallucinogen intoxication
  • hallucinogen persistent perception disorder (flashbacks)
  • hallucinogen intoxication delirium
  • hallucinogen-induced psychotic disorder with delusions
  • hallucinogen-induced psychotic disorder with hallucinations
  • hallucinogen-induced mood disorder
  • hallucinogen-induced anxiety disorder
  • hallucinogen-related disorder not otherwise specified.

Hallucinogen dependence and abuse are normally diagnosed from reports by the patient or person accompanying the patient of the use of a hallucinogenic drug. Active hallucinations and accompanying physical symptoms can confirm the diagnosis, but do not have to be present. Routine drug screening does not detect LSD in the blood or urine, although specialized laboratory methods can detect the drug. Hallucinogen dependence differs from other drug dependence in that there are no withdrawal symptoms when the drug is stopped, and the extent of tolerance (needing a higher and higher dose to achieve the same effect) appears minimal.

Hallucinogen intoxication is diagnosed based on psychological changes, perceptual changes, and physical symptoms that are typical of hallucinogen use. These changes must not be caused by a general medical condition, other substance abuse, or another mental disorder.

Hallucinogen persisting perception disorder, better known as flashbacks, occurs after hallucinogen use followed by a period of lucidity. Flashbacks may occur weeks or months after the drug was used, and may occur after a single use or many uses. To be diagnosed as a psychiatric disorder, flashbacks must cause significant distress or interfere with daily life activities. They can come on suddenly with no warning, or be triggered by specific environments. Flashbacks may include emotional symptoms, seeing colors, geometric forms, or, most commonly, persistence of trails of light across the visual field. They may last for months. Flashbacks are most strongly associated with LSD.

Sidebar: HideShow

A type of drug that causes hallucinations, or distortions in one's perceptions of reality.
Hallucinogen persisting perception disorder—
A formal term for the flashback that some drug users experience after taking hallucinogenic drugs. These flashbacks can occur as long as weeks or months after a drug is taken.
Lysergic acid diethylamide (LSD)—
A potent hallucinogenic drug that is frequently used for recreational purposes.
A naturally occurring plant hallucinogen typically derived from the cactus.
The active ingredient in certain types of mushrooms that have an hallucinogenic effect when ingested.
MDMA (3,4-methylenedioxymethamphetamine)—
A popular hallucinogenic drug commonly referred to as “ecstasy.”

Hallucinogen intoxication delirium is rare unless the hallucinogen is contaminated by another drug or chemical such as strychnine. In hallucinogen intoxication, the patient is still grounded in reality and recognizes that the experiences of altered perception are due to drug use. In hallucinogen intoxication delirium, the patient is no longer grounded in reality. Hallucinogen-induced psychotic disorders are similar in that the patient loses touch with reality. Psychotic states can occur immediately after using the drug, or days or months later.

Hallucinogen-induced mood disorder and hallucinogeninduced anxiety disorder are somewhat controversial, as hallucinogen use may uncover latent or preexisting anxiety or mood disorders rather than being the cause of them. However, it does appear that MDMA use can cause major depression.


Acute treatment is aimed at preventing patients from harming themselves or others. Since most people experiencing hallucinogen intoxication remain in touch with reality, “talking down” or offering reassurance and support that emphasizes the temporary nature of the disturbing sensations and feelings is often helpful. Page 1195  |  Top of ArticlePatients are kept in a calm, pleasant, lighted environment, and are encouraged to move around. Occasionally, drugs such as lorazepam are given for anxiety. Complications in treatment occur when the hallucinogen has been contaminated with other street drugs or chemicals. The greatest life-threatening risk is associated with MDMA, in which users may develop dangerously high body temperatures. Reducing the patient's temperature is an essential acute treatment.

Treatment for long-term effects of hallucinogen use involve long-term psychotherapy after drug use has stopped. Many people find twelve-step programs or group support helpful. In addition, underlying psychiatric disorders must be addressed.


Because hallucinogens are not physically addictive, many people are able to stop using these drugs successfully. However, users may be haunted by chronic problems such as flashbacks or mood and anxiety disorders either brought about or worsened by use of hallucinogens. It is difficult to predict who will have longterm complications and who will not.


Hallucinogen use is difficult to prevent, because these drugs have a reputation for being nonaddictive and “harmless.” Drug education and social outlets that provide people with a sense of self-worth are the best ways to prevent hallucinogen and other substance abuse.

Parental concerns

Many adolescents experiment with hallucinogenic drugs and other illicit substances during their teenage years. Parents should be observant for any changes in their child's behavior, especially those that might suggest he or she could be under the influence of an illicit substance. If parents suspect their children might be experimenting with drugs, they should talk to them and seek out professional help if necessary.



American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed., Washington, D.C.: American Psychiatric Association, 2013.

Galanter, Marc, Herbert D. Kleber, and Kathleen T. Brady, eds. Textbook of Substance Abuse Treatment. 5th ed. Washington, D.C.: American Psychiatric Press, 2014.

Sadock, Benjamin J., ed. Comprehensive Textbook of Psychiatry. 9th ed. Philadelphia: Lippincott Williams & Wilkins, 2012.


Hallock, R.M., et al. “A Survey of Hallucinogenic Mushroom Use, Factors Related to Usage, and Perceptions of Use Among College Students.” Drug and Alcohol Dependence 130, no. 1–3 (June 2013): 245–48.

Móró, L. and Noreika, V. “Sacramental and Spiritual Use of Hallucinogenic Drugs.” The Behavioral and Brain Sciences 34, no. 6 (December 2011): 319–20.


Above the Influence. “Hallucinogens.” Above the Influence. http://abovetheinfluence.com/drugs/hallucinogens (accessed July 17, 2015).

National Institute on Drug Abuse. “DrugFacts: Hallucinogens—LSD, Peyote, Psilocybin, and PCP.” National Institute on Drug Abuse. http://www.drugabuse.gov/publications/drugfacts/hallucinogens-lsd-peyote-psilocybin-pcp (accessed July 17, 2015).

Psychology Today staff. “Hallucinogens.” Psychology Today. https://www.psychologytoday.com/conditions/hallucinogens (accessed July 17, 2015).


National Institute on Drug Abuse, 6001 Executive Blvd, Room 5213, MSC 9561, Bethseda, MD 20892, (301) 443-1124, http://www.drugabuse.gov .

Partnership for a Drug-Free America, 352 Park Ave South, 9th Floor, New York, NY 10010, (212) 922-1560, Fax: (212) 922-1570, http://www.drugfree.org .

Tish Davidson, AM
Emily Jane Willingham, PhD
Revised by Jack Lasky

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

Source Citation

Source Citation   (MLA 8th Edition)
Davidson, Tish, AM, et al. "Hallucinogens and Hallucinogen-Related Disorders." The Gale Encyclopedia of Children's Health: Infancy through Adolescence, edited by Deirdre S. Blanchfield, 3rd ed., vol. 2, Gale, 2016, pp. 1189-1195. Gale Health and Wellness, https%3A%2F%2Flink.gale.com%2Fapps%2Fdoc%2FCX3630900356%2FHWRC%3Fu%3Dmnkanokahs%26sid%3DHWRC%26xid%3D7a94c8be. Accessed 14 Dec. 2019.

Gale Document Number: GALE|CX3630900356