APA (7th ed.) Citation

Rockwell, C., Glanzman, L., & Ley, W. (2006). Danger in Deep Space. Project Gutenberg.

Chicago Style (17th ed.) Citation

Rockwell, Carey, Louis Glanzman, and Willy Ley. Danger in Deep Space. Project Gutenberg, 2006.

MLA (9th ed.) Citation

Rockwell, Carey, et al. Danger in Deep Space. Project Gutenberg, 2006.

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