Columbia subject headings:
Harvard subject headings:
Education, Secondary--Germany--19th century--Congresses.
Education, Secondary--Germany--20th century--Congresses.
Educational change--Germany--History--19th century--Congresses.
Educational change--Germany--History--20th century--Congresses.
High schools--Germany--History--19th century--Congresses.
High schools--Germany--History--20th century--Congresses.
Princeton subject headings:
Education, Secondary--Germany--19th century--Congresses.
Education, Secondary--Germany--20th century--Congresses.
Educational change--Germany--History--19th century--Congresses.
Educational change--Germany--History--20th century--Congresses.
High schools--Germany--History--19th century--Congresses.
High schools--Germany--History--20th century--Congresses.