APA (7th ed.) Citation

Sumner, C., & Billings, E. R. (2011). White Slavery in the Barbary States. Project Gutenberg.

Chicago Style (17th ed.) Citation

Sumner, Charles, and E. R. Billings. White Slavery in the Barbary States. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Sumner, Charles, and E. R. Billings. White Slavery in the Barbary States. Project Gutenberg, 2011.

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