The popularization of LSD outside of the medical world was hastened when individuals such as Ken Kesey participated in drug trials and liked what they saw. Tom Wolfe wrote a widely read account of these early days of LSD's entrance into the non-academic world in his book "The Electric Kool Aid Acid Test", which documented the cross-country, acid-fueled voyage of Ken Kesey and the Merry Pranksters on the psychedelic bus "Furthur" and the Pranksters' later "Acid Test" LSD parties. In 1965, Sandoz laboratories stopped its still legal shipments of LSD to the United States for research and psychiatric use, after a request from the US government concerned about its use. By April 1966, LSD use had become so widespread that "Time Magazine" warned about its dangers. In December 1966, the exploitation film "Hallucination Generation" was released. This was followed by "The Trip" in 1967 and "Psych-Out" in 1968.