Columbia subject headings:
Harvard subject headings:
American fiction--20th century--Bibliography
English fiction--20th century--Bibliography
Espionage in literature--Bibliography.
Spies in literature--Bibliography.
Spy stories, American--Bibliography.
Spy stories, English--Bibliography.
Spy stories--Handbooks, manuals, etc.
Spy stories--Stories, plots, etc.
Princeton subject headings:
American fiction--20th century--Bibliography.
English fiction--20th century--Bibliography.
Spy stories, American--Bibliography.
Spy stories, English--Bibliography.
Spy stories--Stories, plots, etc.