Columbia subject headings:
Leoncavallo, Ruggiero, 1858-1919--Congresses.
Harvard subject headings:
Leoncavallo, Ruggiero, 1858-1919 Pagliacci--Congresses.
Leoncavallo, Ruggiero, 1858-1919--Congresses.
Opera--Italy--Congresses.
Verismo (Opera)--Congresses.
Princeton subject headings: