Hulagu Khan
Boyle, J.A., (Editor). The Cambridge History of Iran: Volume 5, The Saljuq and Mongol Periods . Cambridge University Press; Reissue edition (January 1, 1968). ISBN 0-521-06936-X. Perhaps the best overview of the history of the il-khanate. Covers politics, economics, religion, culture and the arts and sciences. Also has a section on the Isma'ilis, Hulagu's nemesis.