APA (7th ed.) Citation

Ernst, P. (2009). The Planetoid of Peril. Project Gutenberg.

Chicago Style (17th ed.) Citation

Ernst, Paul. The Planetoid of Peril. Project Gutenberg, 2009.

MLA (9th ed.) Citation

Ernst, Paul. The Planetoid of Peril. Project Gutenberg, 2009.

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