APA (7th ed.) Citation

Clark, J. (2010). Penny Nichols and the Mystery of the Lost Key. Project Gutenberg.

Chicago Style (17th ed.) Citation

Clark, Joan. Penny Nichols and the Mystery of the Lost Key. Project Gutenberg, 2010.

MLA (9th ed.) Citation

Clark, Joan. Penny Nichols and the Mystery of the Lost Key. Project Gutenberg, 2010.

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