Columbia subject headings:
Harvard subject headings:
Mendelssohn-Bartholdy, Felix, 1809-1847. Quartets,
Schumann, Robert, 1810-1856. Quartets,
Princeton subject headings:
Mendelssohn-Bartholdy, Felix, 1809-1847.
Modulation.
Schumann, Robert, 1810-1856.
Tonality.