Columbia subject headings:
Harvard subject headings:
Labor literature--Germany--History--19th century.
Labor literature--Germany--History--20th century.
Labor literature--History--19th century.
Labor literature--History--20th century.
Labor unions--Germany--History
Sassenbach, Johannes, 1866-1940--Criticism and interepretation.
Princeton subject headings:
Bibliographers--Germany--Biography.
Labor unions--Germany--Bibliography--History.
Sassenbach, Johannes, 1866-1940.