diff --git a/books/free-programming-books.md b/books/free-programming-books.md
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 * [The Joy of Cryptography (2020)](https://web.engr.oregonstate.edu/~rosulekm/crypto/) - Mike Rosulek (PDF) (:construction: *in process*)
 * [Think Bayes: Bayesian Statistics Made Simple](http://www.greenteapress.com/thinkbayes/) - Allen B. Downey
 * [Think Stats: Probability and Statistics for Programmers](http://greenteapress.com/thinkstats/) - Allen B. Downey (using Python)
+* [Vector calculus](http://www.mecmath.net/calc3book.pdf) - Michael Corral (PDF)
 * [Yet Another Introductory Number Theory Textbook](https://www.poritz.net/jonathan/share/yaintt.pdf) - Jonathan A. Poritz (PDF)