If you'd like to explore the ideas further: Carter's 8 etudes and a fantasy's 7th etude is just the note G (1949) and Ligeti's Musica ricercata's (1951-3) firs

If you'd like to explore the ideas further: Carter's 8 etudes and a fantasy's 7th etude is just the note G (1949) and Ligeti's Musica ricercata's (1951-3) first movement almost only A (the entire work explores having a limited number of notes). In terms of playing with harmonics, the spectralists (starting with Grisey and Murail in the 1970s) originated the idea formally whilst it is informally explored by many minimalists (the most relevant to this article's piece would be Terry Riley's In C, 1964). In terms of mammoth piano works, seek out Sorabji's Opus clavicembalisticum (1930, 4 hours) by John Ogdon.