APA (7th ed.) Citation

Ash, F., & Groome, W. H. C. (2013). A Trip to Mars. Project Gutenberg.

Chicago Style (17th ed.) Citation

Ash, Fenton, and William H. C. Groome. A Trip to Mars. Project Gutenberg, 2013.

MLA (9th ed.) Citation

Ash, Fenton, and William H. C. Groome. A Trip to Mars. Project Gutenberg, 2013.

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