cosponsored by U.S. Geological Survey, Agricultural Research Service, Soil Conservation Serivce, Reston, Virginia, February 5-8, 1990 ; compiled by Madge Ertel
U.S. Dept. of the Interior, U.S. Geological Survey, Bureau of Land Management ; compiled by U.S. Geological Survey Work Group members, A. Dewey Acuff ... [and others]