Columbia subject headings:
Harvard subject headings:
Education, Secondary--Germany--Singen am Hohentwiel--History--20th century.
Educational change--Germany--Singen am Hohentwiel--History--20th century.
Princeton subject headings:
Education, Secondary--Germany--Singen am Hohentwiel--History--20th century.
Educational change--Germany--Singen am Hohentwiel--History--20th century.