In the United States, culdoscopy (a vaginal approach to view the abdomen) replaced laparoscopy for about 20 years, circa 1950-1970. In contrast to many of his colleagues, Hans Frangenheim of Wuppertal, Germany, was not satisfied with culdoscopy and turned to an abdominal approach. Frangenheim began publishing his experiences with gynecological laparoscopy in 1958 and stressed technical improvements. He constructed a CO2 insufflator, wrote the first book on gynecological endoscopy, and introduced "cold light" into laparoscopy. Frangenheim strongly stimulated the rise of gynecological laparoscopy in Europe in the 1960s and later.