APA

Humphrey H. B., . (1961). Makers of North American botany. New York: Ronald.

Chicago

Humphrey Harry Baker, . 1961. Makers of North American botany. New York: Ronald.

Harvard

Humphrey H. B., . (1961). Makers of North American botany. New York: Ronald.

MLA

Humphrey Harry Baker, . Makers of North American botany. New York: Ronald. 1961.