APA (7th ed.) Citation

Todd, D. P. (2012). Astronomy: The Science of the Heavenly Bodies. Project Gutenberg.

Chicago Style (17th ed.) Citation

Todd, David Peck. Astronomy: The Science of the Heavenly Bodies. Project Gutenberg, 2012.

MLA (9th ed.) Citation

Todd, David Peck. Astronomy: The Science of the Heavenly Bodies. Project Gutenberg, 2012.

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