Can't help with German books on the SCW, but here are three in English that are in front of me:
1. "The Spanish Revolution" by Stanley G. Payne, WWNorton & Co., NY 1970. This book gets deep into the social and political tensions that culminated in the SCW, and the first half of its 374 pages of text are spent explaining the factions and movements prior to the start of the war.
2. "The Spanish Civil War" by Hugh Thomas, Harper Brothers, NY 1961. It's been a while since I read this one, but I remember it as a well written general history. It also starts off with explanations of the political factions, and it's only on page 124 (out of 624 of text) that one reaches the critical event of July 13, 1936 (the murder of Calvo Sotelo).
3. "The Passionate War: the Narrative History of the Spanish Civil War" by Peter Wyden, Simon and Schuster, NY 1983. This author gets right to it, reaching the July 13 event on page 32 (out of 523 of text). I'm starting on this one, and it reads well and seems to be very straightforward.
Powell's books in Portland, the USA's largest single bookstore, which also sells books online, has some of these in its Spain section.
Warren B.