Looking at the Spanish Civil War, I found this site, from the University of Nottingham, which is a review of The Butterfly's Tongue with particular reference to the politics of the civil war (the main character's family are strong Republicans, so this has quite a bearing on the narrative). It also has several references to other films on the same subject, which might be useful. Actually, the main site seems to have lots of helpful articles.
On the BFI website I found several articles:
- This is about Mexican cinema...
- This one is quite broad and talks about European Cinema. It recommends some books about Spanish national cinema and European films in general. A book that looks particularly useful is Kinder, Marcia Blood Cinema: the reconstruction of national identity in Spain (Berkeley CA; London: University of California Press), which is about the relation 1980s - 90s film has to Franco and national violence. It also has links to academic journals, world film festivals and websites that might come in handy.