* Add back Calculus by Gilbert Strang
Add working link pointing to the updated 3rd edition of the book.
* Add format
* Change the link to point to the textbook page.
@ -480,6 +480,7 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
* [Bayesian Methods for Hackers](https://github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers) - Cameron Davidson-Pilon
* [Bayesian Methods for Hackers](https://github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers) - Cameron Davidson-Pilon
* [Beginning and Intermediate Algebra](http://www.wallace.ccfaculty.org/book/book.html) - Tyler Wallace
* [Beginning and Intermediate Algebra](http://www.wallace.ccfaculty.org/book/book.html) - Tyler Wallace
* [Book of Proof](https://www.people.vcu.edu/~rhammack/BookOfProof/) - Richard Hammack [(PDF)](https://www.people.vcu.edu/~rhammack/BookOfProof/Main.pdf)
* [Book of Proof](https://www.people.vcu.edu/~rhammack/BookOfProof/) - Richard Hammack [(PDF)](https://www.people.vcu.edu/~rhammack/BookOfProof/Main.pdf)