APA (7th ed.) Citation

Flammarion, C., & Welby, F. A. (2008). Astronomy for Amateurs. Project Gutenberg.

Chicago Style (17th ed.) Citation

Flammarion, Camille, and Frances A. Welby. Astronomy for Amateurs. Project Gutenberg, 2008.

MLA (9th ed.) Citation

Flammarion, Camille, and Frances A. Welby. Astronomy for Amateurs. Project Gutenberg, 2008.

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