APA (7th ed.) Citation

Kennon, J. L. (1996). The Planet Mars and Its Inhabitants, a Psychic Revelation. Project Gutenberg.

Chicago Style (17th ed.) Citation

Kennon, J. L. The Planet Mars and Its Inhabitants, a Psychic Revelation. Project Gutenberg, 1996.

MLA (9th ed.) Citation

Kennon, J. L. The Planet Mars and Its Inhabitants, a Psychic Revelation. Project Gutenberg, 1996.

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