Columbia subject headings:
Composers--Germany--Krefeld--Biography.
Music--Germany--Krefeld--20th century--Bio-bibliography.
Music--Germany--Krefeld--20th century--History and criticism.
Harvard subject headings:
Composers--Germany--Krefeld--Biography.
Music--Germany--Krefeld--20th century--Bio-bibliography.
Music--Germany--Krefeld--20th century--History and criticism.
Princeton subject headings: