Geographic coverage by soil conservation district. "Interpretations derived from soil map constructed ... by Cartographic Division, Soil Conservation Service, USDA ... of Puerto Rico."" ""Base source: USGS base map 1:100,000 dated 1979." Includes location map and notes., 17 maps : color ; 92 x 123 cm or smaller, Scale 1:50,000
United States. Soil Conservation Service (1981). Important Farmlands...Puerto Rico. United States. Soil Conservation Service. http://cdm17287.contentdm.oclc.org/cdm/ref/collection/maps1/id/33612 (map)