APA (7th ed.) Citation

Lewis, I. M. (2014). Astronomy for Young Folks. Project Gutenberg.

Chicago Style (17th ed.) Citation

Lewis, Isabel Martin. Astronomy for Young Folks. Project Gutenberg, 2014.

MLA (9th ed.) Citation

Lewis, Isabel Martin. Astronomy for Young Folks. Project Gutenberg, 2014.

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