Columbia subject headings:
Harvard subject headings:
German language--Self-instruction--Congresses.
German language--Textbooks for foreign speakers--English--Congresses.
Philanthropists--Germany--Biography--Congresses.
Self-culture--History--Congresses.
Princeton subject headings:
German language--Self-instruction--Congresses.
German language--Textbooks for foreign speakers--English--Congresses.
Philanthropists--Germany--Biography--Congresses.
Self-culture--History--Congresses.