TY  - RPRT
TI  - Water-quality trends in the nation's rivers
AU  - Richard A. Smith
AU  - Richard B. Alexander
AU  - M. G. Wolman
PY  - 1987
DO  - 10.1126/science.235.4796.1607
UR  - https://pubs.usgs.gov/publication/70015321
ID  - 70015321
ER  -