O'Callaghan, J. F. (1993). The learned king: The reign of Alfonso X of Castile. University of Pennsylvania Press.
Chicago-referens (17:e uppl.)O'Callaghan, Joseph F. The Learned King: The Reign of Alfonso X of Castile. Philadelphia: University of Pennsylvania Press, 1993.
MLA-referens (9:e uppl.)O'Callaghan, Joseph F. The Learned King: The Reign of Alfonso X of Castile. University of Pennsylvania Press, 1993.
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