This via r/programming today: A non-standard book list for software developers:
- Euclid’s Elements
- Calculus, 4th edition (the article above references the 3rd edition, not sure why, also there is an answer book)
- Operating System Design: The Xinu Approach, Second Edition
- Lisp in Small Pieces
Also some bonus material mentioned: Calculus Revisited: Single Variable Calculus video lectures from the late MIT lecturer Herb Gross.