APA (7th ed.) Citation

Sumner, C. (2007). The Best Portraits in Engraving. Project Gutenberg.

Chicago Style (17th ed.) Citation

Sumner, Charles. The Best Portraits in Engraving. Project Gutenberg, 2007.

MLA (9th ed.) Citation

Sumner, Charles. The Best Portraits in Engraving. Project Gutenberg, 2007.

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