APA

Bessey C. e., . (1968). The evolution and classification of flowering plants. New York: Houghton Mifflin Company.

Chicago

Bessey Charles e, . 1968. The evolution and classification of flowering plants. New York: Houghton Mifflin Company.

Harvard

Bessey C. e., . (1968). The evolution and classification of flowering plants. New York: Houghton Mifflin Company.

MLA

Bessey Charles e, . The evolution and classification of flowering plants. New York: Houghton Mifflin Company. 1968.