Columbia subject headings:
Harvard subject headings:
Abel, Karl, 1897-1971.
Communists--Germany--Biography
Kommunistische Partei Deutschlands--Biography.
Politicians--Germany--Biography
Socialists--Germany--Biography
Princeton subject headings:
Abel, Karl, 1897-1971.
Communists--Germany--Biography.
Kommunistische Partei Deutschlands--Biography.
Politicians--Germany--Biography.
Socialists--Germany--Biography.