Columbia subject headings:
Harvard subject headings:
Bulgaria--Ethnic relations--Sources.
Jews--Bulgaria--History--20th century--Sources.
World War, 1939-1945--Jews--Rescue--Bulgaria--Sources.
Princeton subject headings:
Bulgaria--Ethnic relations--Sources.
Jews--Bulgaria--History--20th century--Sources.
World War, 1939-1945--Jews--Rescue--Bulgaria--Sources.