Clarke, P. D., & Duggan, A. (2012). Pope Alexander III (1159 - 81): The art of survival. Ashgate.
Cita Chicago Style (17a ed.)Clarke, Peter D., y Anne Duggan. Pope Alexander III (1159 - 81): The Art of Survival. Farnham, Surrey Burlington, VT: Ashgate, 2012.
Cita MLA (9a ed.)Clarke, Peter D., y Anne Duggan. Pope Alexander III (1159 - 81): The Art of Survival. Ashgate, 2012.
Precaución: Estas citas no son 100% exactas.