TY  - RPRT
TI  - Potassium and thorium maps of the conterminous United States
AU  - J. S. Duval
AU  - W. J. Jones
AU  - F.R. Riggle
AU  - J. A. Pitkin
PY  - 1990
DO  - 10.3133/ofr90338
UR  - https://pubs.usgs.gov/publication/ofr90338
ID  - ofr90338
ER  -