APA (7th ed.) Citation

Hooker, B., Hastings, W., & Booth, H. (2011). The Professor's Mystery. Project Gutenberg.

Chicago Style (17th ed.) Citation

Hooker, Brian, Wells Hastings, and Hanson Booth. The Professor's Mystery. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Hooker, Brian, et al. The Professor's Mystery. Project Gutenberg, 2011.

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