APA (7th ed.) Citation

Landon, H. (2011). The Gray Phantom's Return. Project Gutenberg.

Chicago Style (17th ed.) Citation

Landon, Herman. The Gray Phantom's Return. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Landon, Herman. The Gray Phantom's Return. Project Gutenberg, 2011.

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