APA (7th ed.) Citation

Apgar, A. C. (2009). Trees of the Northern United States Their Study, Description and Determination. Project Gutenberg.

Chicago Style (17th ed.) Citation

Apgar, A. C. Trees of the Northern United States Their Study, Description and Determination. Project Gutenberg, 2009.

MLA (9th ed.) Citation

Apgar, A. C. Trees of the Northern United States Their Study, Description and Determination. Project Gutenberg, 2009.

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