Gail, Marzieh, The three Popes; an account of the great schism when rival Popes in Rome, Avignon, and Pisa vied for the rule of Christendom. [print] - New York, Simon and Schuster (c)1969. - 320 pages illustrations 25 cm. LCCN: 79075861 LC Class. No.: BX1301.G138.T474 1969 BX1301