Textbook
Ph 136a (and 136b,c) is primarily based on the text Applications of Classical Physics by Kip Thorne and Roger Blandford. It grew over some 30 years out of their notes for this course at Caltech. The concise 1,511-page, 3.5kg book was published in August 2017 by Princeton University Press. For those challenged by the 3.5kg of the physical book, it is available for purchase on kindle and is also loaded on all of the Caltech library's Kindle readers, which may be checked out for one week at a time.
You may find online pdf copies of decades-old drafts of the text. However the final version differs in many places from those, some serious errors were corrected, the Chapter divisions differ, and the wording and numbering of the homework problems also differ, so I do not advise using those old materials.
Lecture notes, and recordings of the lectures and homework help sessions are published in Canvas, accessible to registered students of Ph 136a.