APA (7th ed.) Citation

Alighieri, D., Ciardi, J., MacAllister, A. T., & Cifelli, E. M. The purgatorio.

Chicago Style (17th ed.) Citation

Alighieri, Dante, John Ciardi, Archibald T. MacAllister, and Edward M. Cifelli. The Purgatorio. New York.

MLA (9th ed.) Citation

Alighieri, Dante, et al. The Purgatorio.

Warning: These citations may not always be 100% accurate.