United States Department of Agriculture, Natural Resources Conservation Service ; in cooperation with Virginia Polytechnic Institute and State University, and United States Department of Agriculture, Forest Service
United States Department of Agriculture, Soil Conservation Service : in cooperation with United States Department of Agriculture, Forest Service, and the Virginia Polytechnic Institute and State University
United States Department of Agriculture, Soil Conservation Service ; in cooperation with Virginia Polytechnic Institute and State University, and United States Department of Agriculture, Forest Service