Who's Who in CIA is a book written by the East German journalist Julius Mader (also known by the alias Thomas Bergner) and published in East Berlin in 1968, under Stasi auspices and probably with KGB assistance. Mader was employed by the East German military publishing house and apparently had access to some information on CIA officers that was not publicly available. The book purported to identify about 3,000 active agents of the U.S. Central Intelligence Agency. It was modeled after other Who's Who guides.