The original materials for the crusade of Frederic II. may be drawn from Richard de St. Germano (in Muratori, Script. Rerum Ital. tom. vii. p. 1002 - 1013) and Matthew Paris (p. 286, 291, 300, 302, 304). The most rational moderns are Fleury (Hist. Eccles. tom. xvi.), Vertot (Chevaliers de Malthe, tom. i. l. iii.), Giannone (Istoria Civile di Napoli, tom. ii. l. xvi.), and Muratori (Annali d' Italia, tom. x).