APA (7th ed.) Citation

Lucas, F. A. (2011). Animals of the Past. Project Gutenberg.

Chicago Style (17th ed.) Citation

Lucas, Frederic A. Animals of the Past. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Lucas, Frederic A. Animals of the Past. Project Gutenberg, 2011.

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