M20 - M39 piano solo
M21 collections - works of two or more composers
M22 collections - works of one composer
M23 sonatas
M24 suites
M26 works for piano one hand
M27 theme and variations
M28 - M32 marches and dances
M198 - M216 Duets (piano only)
M200 - M212 piano, four hands
M213 piano, five, six, eight etc. hands
M217 - M285 duets (piano and another instrument)
M310 - M344 piano and two other instruments
M410 - M449 piano and three other instruments
M510 - M549 piano and four other instruments
(follow the same for five, six, etc. other instruments)
M1010 piano with orchestra (full score)
M1011 piano with orchestra (two-piano version)
M1110 piano with string orchestra
M1111 piano with string orchestra (two-piano version)
ML650 - ML746 Books about the piano
MT220 - MT258 studies and methods / instruction
A seat at the piano (promoting inclusion in piano repertoire)