CIA File of the Day
The Berlin Tunnel Operation 1952-1956
Clandestine Services History paper no. 150, prepared on 25 August 1967 and published on 24 June 1968. It is the official history of the Berlin Tunnel operation (also called PBJOINTLY) from 1952 to 1956, covering planning, implementation, termination, production, and aftermath.
Courtesy of the CIA FOIA Electronic Reading Room. Official page: CIA FOIA Electronic Reading Room. Copy: Internet Archive.