Columbia subject headings:
Music--Instruction and study--Germany--Rhineland--20th century.
School music--Germany--Rhineland--20th century.
Harvard subject headings:
Music--Instruction and study--Germany--Rhineland--20th century--Congresses.
Pedagogy (Music)--Germany--Rhineland--20th century--Congresses.
School music--Instruction and study--Germany--Rhineland--20th century--Congresses.
Princeton subject headings:
Music--Instruction and study--Germany--Rhineland--History--Congresses.