Columbia subject headings:
Hackmann, Heinrich Friedrich, 1864-1935.
Religion historians--Biography.
Harvard subject headings:
Hackmann, Heinrich Friedrich, 1864-1935--Bibliography.
Hackmann, Heinrich Friedrich, 1864-1935.
Religion historians--Biography.
Religionsgeschichtliche Schule.
Religious biography--Germany.
Theology, Doctrinal--Germany--History--20th century.
Princeton subject headings: