Columbia subject headings:
Forced labor--Soviet Union.
Internment camps--Soviet Union.
Nazi concentration camps--Soviet Union.
Prisons--Soviet Union.
Harvard subject headings:
Concentration camps--Soviet Union--Directories.
Forced labor--Soviet Union--History
Imprisonment--Soviet Union--History.
Prisons--Soviet Union--Directories.
Princeton subject headings:
Prisons--Soviet Union--Directories.