APA

Crum H. A., Steere W. C., . (1957). The mosses of Porto Rico and the Virgin Islands. New York: The Academy.

Chicago

Crum Howard Alvin, Steere William Campbell, . 1957. The mosses of Porto Rico and the Virgin Islands. New York: The Academy.

Harvard

Crum H. A., Steere W. C., . (1957). The mosses of Porto Rico and the Virgin Islands. New York: The Academy.

MLA

Crum Howard Alvin, Steere William Campbell, . The mosses of Porto Rico and the Virgin Islands. New York: The Academy. 1957.