Columbia subject headings:
Harvard subject headings:
Communists--Germany--Correspondence.
Kommunistische Partei Deutschlands--History.
Stalin, Joseph, 1878-1953--Correspondence.
Thälmann, Ernst, 1886-1944--Correspondence.
Princeton subject headings:
Communism--Germany--History--20th century.
Kommunistische Partei Deutschlands--History--Sources.
Thälmann, Ernst, 1886-1944.