TY  - RPRT
TI  - Modern aerial gamma-ray spectrometry and regional potassium map of the conterminous United States
AU  - Joseph S. Duval
PY  - 1990
DO  - 10.1016/0375-6742(90)90076-m
UR  - https://pubs.usgs.gov/publication/70015815
ID  - 70015815
ER  -