APA (7th ed.) Citation

Little, E. L., Woodbury, R. O., & Wadsworth, F. H. Trees of Puerto Rico and the Virgin Islands. Dep. of Agriculture.

Chicago Style (17th ed.) Citation

Little, Elbert Luther, Roy O. Woodbury, and Frank H. Wadsworth. Trees of Puerto Rico and the Virgin Islands. Washington, DC: Dep. of Agriculture.

MLA (9th ed.) Citation

Little, Elbert Luther, et al. Trees of Puerto Rico and the Virgin Islands. Dep. of Agriculture.