APA (7th ed.) Citation

Stratemeyer, E., & Optic, O. (2008). An Undivided Union. Project Gutenberg.

Chicago Style (17th ed.) Citation

Stratemeyer, Edward, and Oliver Optic. An Undivided Union. Project Gutenberg, 2008.

MLA (9th ed.) Citation

Stratemeyer, Edward, and Oliver Optic. An Undivided Union. Project Gutenberg, 2008.

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