History of Catholicism in Spain
- A collection of open source Wikipedia articles on the history of the Catholic Church in Spain.
- http://en.wikipedia.org/wiki/Category:History_of_Catholicism_in_Spain

Carlism's Defense of the Church in Spain, 1833-1936
- An article by Alexandra Wilhemson.
- http://www.ewtn.com/library/HUMANITY/FR90403.TXT

But What About the Faith? Catholicism and Liberalism in Nineteenth Century Spain
- by Patrick Foley. A retrospective look at the Carlist movement and its contributions to the battle for the soul of Spain in the tidal wake of the French Revolution.
- http://www.ewtn.com/library/HUMANITY/FR90402.TXT

The Episcopate in the Kingdom of Leon the Twelfth Century
- Full text online of 1978 book by Richard A. Fletcher.
- http://libro.uca.edu/ekl/main.htm