http://www.amazon.co.uk/Anarchism-Re.../dp/1845451767
This is good for understanding the nascent development of anarcho-syndicalism in pre-war Catalonia. Murray Bookchin wrote a history of anarchism in Spain, focused on the Civil War, but I'm pretty sure that's available to read online. Contemporary anarchists like Juan Gomez Casas and Anselmo Lorenzo wrote accounts, Casas' book Anarchist Organisation was a history of the CNT/FAI and Lorenzo Anselmo wrote an autobiography called the Militant Proletariat. Anarchism in Spain wasn't just unique to Catalonia though, so you should read around Asturias and Andalusia etc. as well.