APA (7th ed.) Citation

Allen, E. A. (2001). The Prehistoric World; Or, Vanished races. Project Gutenberg.

Chicago Style (17th ed.) Citation

Allen, Emory Adams. The Prehistoric World; Or, Vanished Races. Project Gutenberg, 2001.

MLA (9th ed.) Citation

Allen, Emory Adams. The Prehistoric World; Or, Vanished Races. Project Gutenberg, 2001.

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