APA

Steenbergh W. F., Lowe C. H., . (1977). Ecology of the saguaro II. Tucson: National Park Service.

Chicago

Steenbergh Warren F, Lowe Charles H, . 1977. Ecology of the saguaro II. Tucson: National Park Service.

Harvard

Steenbergh W. F., Lowe C. H., . (1977). Ecology of the saguaro II. Tucson: National Park Service.

MLA

Steenbergh Warren F, Lowe Charles H, . Ecology of the saguaro II. Tucson: National Park Service. 1977.