I have a copy of a book in the 'Secret Projects' series about military spacecraft projects titled Secret Projects: Military Space Technology, written by Bill Rose, and it can be purchased online at this link: This book talks about the different design studies for military spacecraft, ranging from the Eugen Sanger's Silbervogel suborbital bomber to the Manned Orbital Laboratory and X-20 Dynasoar to anti-satellite missiles to a gigantic troop transport spacecraft.
