APA (7th ed.) Citation

Burroughs, E. R., & Schoonover, F. E. (2009). The Gods of Mars. Project Gutenberg.

Chicago Style (17th ed.) Citation

Burroughs, Edgar Rice, and Frank Earle Schoonover. The Gods of Mars. Project Gutenberg, 2009.

MLA (9th ed.) Citation

Burroughs, Edgar Rice, and Frank Earle Schoonover. The Gods of Mars. Project Gutenberg, 2009.

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