If you want to get into Osprey-like coverage of the men and the planes, ships, tanks guns & uniforms (and eitehr like looking at pics or can handle at least captions in Spanish) I would highly recommend:
'Atlas Illustrado de Armas y Uniformes de la Guerra Civil Espanola' by Lucas M Franco (!) and José M García (publ Susaeta)
The same publisher's 'Guerra Civil Espanola -Fotographias Inéditas' is a very good source of photographs, produced large-format, some harrowing, all well-chosen.
Paul Preston has several good books in print on the war, tho I find Beeover's work rather more objective and less inclined to emphasise Nationalist excesses while seeming inclined to minimise or make excuses for those of the Republicans. A controversial business.