; Joseph Hergenröther, "Leonis X Pontificis Maximi Regesta" (Freiburg, 1884-); "Regesta Clementis Papæ V cura et studio monachorum ordinis S. Benedicti" (Rome, 1885-); Pressuti, "Registrum Honorii III" (Rome, 1888-).There are innumerable collections of papal letters issued from a partisan point of view.