Music theory
Helpful Books
Music Theory Companion
PG App Studio
Music Theory Helper
johgru apps
Theory of music
Kirill Sidorov
MyMusicTheory - music theory
myrApps s.r.o.
Audio & Music Player
JRT Studio Music Players
Math theory
Sangakoo
Probability theory
N9q5DgBw
Set theory
Perfect Ear: Music & Rhythm
Crazy Ootka Software AB