APA (7th ed.) Citation

Archer, W. (2009). Gems (?) of German Thought. Project Gutenberg.

Chicago Style (17th ed.) Citation

Archer, William. Gems (?) of German Thought. Project Gutenberg, 2009.

MLA (9th ed.) Citation

Archer, William. Gems (?) of German Thought. Project Gutenberg, 2009.

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