Found in 3 comments on Hacker News
org3432 · 2018-12-01 · Original thread
This was the book that Richard Feynman used to teach himself calculus when he was 10 or 11 as I recall:
chii · 2017-04-25 · Original thread
I dont know if the book you had was correct, but in one of his interviews, Feynmen had mentioned he used a book called 'calculus for the practical man' ( i think.
rhgraysonii · 2015-06-14 · Original thread
I would recommend starting with a calculus book. If you aren't comfortable enough with the trig side of things, do a refresher on OCW or Khan Academy.

This book is my personal favorite.

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