Cassell, A. K., Dante Alighieri, & Vernani, G. (2004). The Monarchia controversy: An historical study with accompanying translations of Dante Alighieri's Monarchia, Guido Vernani's Refutation of the Monarchia composed by Dante and Pope John XXII's bull, Si fratrum. Catholic University of America Press.

Cassell, Anthony K., Dante Alighieri, and Guido Vernani. The Monarchia Controversy: An Historical Study with Accompanying Translations of Dante Alighieri's Monarchia, Guido Vernani's Refutation of the Monarchia Composed by Dante and Pope John XXII's Bull, Si Fratrum. Washington, D. C.: Catholic University of America Press, 2004.

Cassell, Anthony K., et al. The Monarchia Controversy: An Historical Study with Accompanying Translations of Dante Alighieri's Monarchia, Guido Vernani's Refutation of the Monarchia Composed by Dante and Pope John XXII's Bull, Si Fratrum. Catholic University of America Press, 2004.