E. L.  Little, Jr, Woodbury, R. O., and Wadsworth, F. H., ?Trees of Puerto Rico and the Virgin Islands 2?, Agricultural Handbook of the  U.S. Department of Agriculture Washington, D.C.Agricultural Handbook of the  U.S. Department of Agriculture Washington, D.C., vol. 449, pp. 170-181; pl. 319-324, 1974.