TY  - RPRT
TI  - Resources for the twenty-first century - Proceedings of the International centennial symposium of the United States Geological Survey, held at Reston, Virginia, October 14-19, 1979
AU  - M.E. Williams
PY  - 1982
DO  - 10.3133/pp1193
UR  - https://pubs.usgs.gov/publication/pp1193
ID  - pp1193
ER  -