This is a seminal book and monumental work on the history, the (then) current methods, organization, goals, of Soviet espionage — i.e., KGB foreign intelligence with its First Chief Directorate — and internal security operations — i.e., the Second Chief Directorate.(1)
The author, John D. Barron (1930-2005), was an American investigative journalist, a brilliant Reader's Digest writer and editor, and one of the foremost scholars of Soviet espionage during the Cold War. He also wrote Operation Solo: The FBI's Man in the Kremlin(Regnery, 1996). He was an American patriot.
This book detailed and exposed all the KGB officers posted across the world who were then known to the Western security services. The KBG counted with a disinformation campaign slandering Barron, calling him a fake and his book a fabricated Zionist conspiracy! The fact, as later admitted by KGB Officer Oleg Nechiporenko, is that Barron's publication in 1974 of KGB — The Secret Work of the Soviet Secret Agents dealt a crushing blow to KGB operations throughout the world! During the decade of the 1970s, its publication was one of the few intelligence successes of the West against the Soviets.