Columbia subject headings:
Boyce, Christopher John.
Spies--Soviet Union--Biography.
Spies--United States--Biography.
Harvard subject headings:
Boyce, Christopher John.
Spies--Soviet Union--Biography.
Spies--United States--Biography.
Princeton subject headings:
Boyce, Christopher John.
Spies--Soviet Union--Biography.
Spies--United States--Biography.