APA (7th ed.) Citation

Marlowe, S., & McCauley, H. W. (2010). Prison of a Billion Years. Project Gutenberg.

Chicago Style (17th ed.) Citation

Marlowe, Stephen, and Harold W. McCauley. Prison of a Billion Years. Project Gutenberg, 2010.

MLA (9th ed.) Citation

Marlowe, Stephen, and Harold W. McCauley. Prison of a Billion Years. Project Gutenberg, 2010.

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