Columbia subject headings:
Harvard subject headings:
Bulgaria--Foreign relations--Germany (East)
Bulgaria--Politics and government--1944-1990.
Bulgaria. Dŭrzhavna sigurnost.
Germany (East)--Emigration and immigration.
Germany (East)--Foreign relations--Bulgaria.
Germany (East)--Politics and government.
Germany (East). Ministerium für Staatssicherheit.
Refugees--Germany (East)--History--20th century.
Secret service--Bulgaria--History--20th century.
Secret service--Germany (East)--History--20th century.
Princeton subject headings:
Bulgaria--History--1944-1990.
Bulgaria. Komitet za Dăržavna sigurnost.
Escapes--Germany (East).
Germany (East). Ministerium für Staatssicherheit