Spanish Army and Police Uniforms in 1920s and '30s

[Onebigriver]

At some point I want to do some Cthulhu skirmish wargaming, originally I was going to use the Innsmouth setting, but after seeing "Dagon", I've decided to set it in Spain in the 1920s/30s, allowing me to use my Sharp Practice buildings. It will be set pre-Civil War, and I imagine I can use alot of civil war figures for the armed forces, but I was wondering if the Osprey Spanish Civil War book covers uniforms pre-civil war for the army and armed police forces, or even if there were any changes at the outbreak of the civil war, seeing as soldiers and police ended up on both sides?