Columbia subject headings:
Mendelssohn-Bartholdy, Felix, 1809-1847--Friends and associates--Congresses.
Harvard subject headings:
Mendelssohn-Bartholdy, Felix, 1809-1847--Friends and associates--Congresses.
Princeton subject headings:
Mendelssohn-Bartholdy, Felix, 1809-1847--Friends and associates--Congresses.