referred to as transsexual or transgender as separate from the categories of homosexuality, he referred to these people as transvestiten (transvestites). Germany's dominance in sexual behavior research ended with the Nazi regime. The Institute and its library were destroyed by the Nazis less than three months after they took power, May 8, 1933. The institute was shut down and Hirschfeld's books were burned. Other sexologists in the early gay rights movement included Ernst Burchard and Benedict Friedlaender. Ernst Gräfenberg, after whom the G-spot is named, published the initial research developing the intrauterine device (IUD). Post WWII After World War II, sexology experienced a renaissance, both in the United States and Europe. Large scale studies of sexual behavior, sexual function, and sexual dysfunction gave rise to the development of sex therapy. Post-WWII sexology in the U.S. was influenced by the influx of European refugees escaping the Nazi regime and the popularity of the Kinsey studies. Until that time, American sexology consisted primarily of groups working to end prostitution and to educate youth about sexually transmitted diseases. Alfred Kinsey founded the Institute for Sex Research at Indiana University at Bloomington in 1947. This is now called the Kinsey Institute for Research in Sex, Gender and Reproduction. He wrote in his 1948 book that more was scientifically known about the sexual behavior of farm animals than of humans. Psychologist and sexologist John Money developed theories on sexual identity and gender identity in the 1950s. His work, notably on the David Reimer case has since been regarded as controversial, even while the case was key to the development of treatment protocols for intersex infants and children. Kurt Freund developed the penile plethysmograph in Czechoslovakia in the 1950s. The device was designed to provide an objective measurement of sexual arousal in males and is currently used in the assessment of pedophilia and hebephilia. This tool has since been used with sex offenders. In 1966 and 1970, Masters and Johnson released their works Human Sexual Response and Human Sexual Inadequacy, respectively. Those volumes sold well, and they were founders of what became known as the Masters & Johnson Institute in 1978. Vern Bullough was a historian of sexology during this era, as well as being a researcher in the field. The emergence of HIV/AIDS in the 1980s caused a dramatic shift in sexological research efforts towards understanding and controlling the spread of the disease. 21st century