Béla Bartók (1881-1945)
The piano pieces from Béla Bartók's For Children (1909) and Mikrokosmos (1926/39) were among the first I played as a boy. They introduce any young pianist to compositional technique, as well as piano playing skills. (Bartok and his pal Zoltán Kodaly both understood the importance of and contributed so much to, education.) Thanks to his accessible pieces with uncompromising harmony, I learned about 20th-century chord structure.
Later at university we did detailed analyses of Bartók's Music for Strings, Percussion & Celesta (1936) and I listened to his Concerto for Orchestra (1945), 44 Duos for 2 Violins (1931), The Miraculous Mandarin (1931) and his String Quartets.
Writings on Bartók describe how he used parlando rubato folk style, Fibonacci sequence, golden section, prime numbers, symmetry, asymmetry and opposing tonalites. These features sometimes affect my music.