* Add Math Books from aimath.org
* Fix Trailing Slashes
* Fix Alphabetical Order?
* Fix Alphabetical Order
* Fixed language and categories
* Fixed language and categories for -ko.md
* Removed most PDF links from addition.
* Replace German Resource with Direct Link to PDF
* Remove dead link to "The Standard Python Library"
The link to the book "The Standard Python Library" hosted on effbot.org is dead, and I could not find another source that legally hosts that book.
* Update free-programming-books.md
The link to the book "The Standard Python Library" hosted on effbot.org is dead:
http://effbot.org/librarybook/
This change updates it to the one at archive.org.
* Fix Contributing.md broken link
* Fixed broken links in free-programming-books-pt_BR.md
* Removed the broken link
There is no other link found, related to the book.
* Added vector calculus book