Subject
Espionage
History
113
Spies
76
Intelligence service
68
Secret service
31
Cold War
22
World War, 1939-1945
21
Foreign relations
19
Subversive activities
16
Politics and government
14
Espionage, Soviet
13
Military intelligence
13
Communism
8
Prevention
7
Terrorism
7
Electronic surveillance
6
Moral and ethical aspects
6
National security
6
World War, 1914-1918
6
Officials and employees
5
Equipment and supplies
4
Law and legislation
4
Political aspects
4
Presidents
4
World politics
4
Anti-communist movements
3
Arab-Israeli conflict
3
Assassins
3
Confidential communications
3
Espionage, American
3
Fedayeen
3
History, Modern
3
Informers
3
Intelligence officers
3
International relations
3
Invisible inks
3
Journalists
3
Military interrogation
3
Motion pictures
3
Police
3
Press and politics
3
Women communists
3
Women spies
3
Writing, Invisible
3
Aesthetics
2
Anti-Nazi movement
2
Biography
2
Business intelligence
2
Catholics
2
Characters
2
more ...