Studies of tropical American ferns.

MLA

Maxon, William R. Studies of Tropical American Ferns. Washington: Govt. Print. Off., 1908.

APA

Maxon, W. R. (1908). Studies of tropical American ferns. Washington: Govt. Print. Off.

Chicago

Maxon, William R. Studies of Tropical American Ferns. Washington: Govt. Print. Off., 1908.