All notes
Elliptic functions and their friends
List of simple but counterintuitive math things
Insane trigonometric identities
Упражнения для сестры, часть 1
Упражнения для сестры, часть 2
Useful German vocab for math writing
Derivation of the Weierstrass elliptic integral periods
Pi and the AGM: Exercises 1.1
Pi and the AGM: Exercises 1.2