APA (7th ed.) Citation

Allies, T. W. (2010). Peter's Rock in Mohammed's Flood, from St. Gregory the Great to St. Leo III. Project Gutenberg.

Chicago Style (17th ed.) Citation

Allies, T. W. Peter's Rock in Mohammed's Flood, from St. Gregory the Great to St. Leo III. Project Gutenberg, 2010.

MLA (9th ed.) Citation

Allies, T. W. Peter's Rock in Mohammed's Flood, from St. Gregory the Great to St. Leo III. Project Gutenberg, 2010.

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