APA (7th ed.) Citation

(1916). Studies of tropical American ferns, No. 6. GPO.

Chicago Style (17th ed.) Citation

Studies of Tropical American Ferns, No. 6. [Washington]: GPO, 1916.

MLA (9th ed.) Citation

Studies of Tropical American Ferns, No. 6. GPO, 1916.

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