Tolong jelaskan mengenai Sumber dari Baudouin IV dari Yerusalem

William of Tyre, A History of Deeds Done Beyond the Sea. E. A. Babcock and A. C. Krey, trans. Columbia University Press, 1943.

Steven Runciman, A History of the Crusades, vol. II: The Kingdom of Jerusalem. Cambridge University Press, 1952.

Dana Carleton Munro, The Popes and the Crusades. American Philosophical Society, Proceedings of the American Philosophical Society Vol. 55, No. 5 pp. 348-356 (1916).