I have just finished the first two chapters in my textbook on time travel!
The main page for the textbook is here: http://www.scp-wiki.net/time-travel
You can follow the links from the main page, or here are the links for each chapter.
Chapter 1: Introduction to Time Travel: http://www.scp-wiki.net/time-travel-ch1
Chapter 2: Time Loops: http://www.scp-wiki.net/time-travel-ch2
Note, if you are interested, I am willing to accept chapters on additional time travel topics from other authors. If you want to write a chapter for the book, reply or PM or find me in chat so we can discuss it.