The book that was used as a reference in writing all other books about rocket propulsion. I paid over 100.00 for my copy, I was talking to a Mines student about the book and that I may have to replace my copy and he showed my this like from MIT. It is a must to download if you are interested in, have been doing research rocketry or enjoy a good read on those sleepless night. There is a lot of information about so many things. Solid Propellant Rocket Fundamentals start on 417 but there is a bunch of other information very useful.