BMW is a fun one! It is definitely meant for Air Force cadets in the early 70s (and the introduction says as much) so it's pretty approachable with a college freshman physics and calc background. The final "homework problem" is to stitch together the radar ranging, orbit determination, Lambert problem solving, and rocket guidance assignments from the previous chapters into a complete ICBM defense system. Pretty wild.…
It's a Dover edition. They love getting textbooks that are decades old and making inexpensive but decent quality paperback editions. In fast moving fields Dover editions may be out of date, but if the fundamentals haven't changed much a Dover book can be a great way to get started.
To a good first approximation if you are interested in some area of STEM and would be fine with an approach that doesn't include the last couple of decades are so of developments Dover is a good place to start.