The first paper on HIV/AIDS, reporting on June 5, 1981 on five cases of Pneumocystis carinii pneumonia (PCP) seen at the University of California at Los Angeles (UCLA) medical center. PCP was then a rare infection; however, the lead author of the paper, Michael Gottlieb, had seen five cases of this infection since January 1981, all in previously healthy young homosexual men, indicating that their immune system was not working. (Thanks to Juan Weiss for this reference.)