 Here's the list of sources I use to put together the How Fast Is It? video book. These books, videos, and websites also represent resources you can use to do further research. The meaning of relativity is Einstein's own book on the subject. It's a worthwhile read, even if you don't do the math. Kip Thorn's book, The Science of Interstellar, covers the science behind the movie. It's a great resource for understanding black holes. Elementary Differential Geometry by Barad O'Neill was the textbook I used at San Diego State University. It is well written and covers the foundations and geometry needed for a deeper understanding of general relativity. Another good college textbook is Concepts of Modern Physics by Arthur Breezer. There are two particularly useful sources for learning about relativity theory. One of them is the Stanford University YouTube series presented by Leonard Suskind. I used it extensively, but it assumes a deep understanding of the math. Better yet, for those who are not familiar with differential equations, Dr. John D. Norton's website is outstanding. Norton has a deep understanding of the subject matter and discusses it in non-mathematical terms. I used his examples extensively. For gravitational waves, there is no better source than the LIGO site itself, as well as the associated Caltech and MIT site. They have created resources usable by everyone from middle school to postdoctoral students. It also has an outreach facility for teachers. And don't forget, every How Fast Is It video segment has a document with the text, links, music, pictures and notes located on howfarawayisit.com slash documents. The following identifies all of my sources. Thanks for watching.