TY  - RPRT
TI  - Terrestrial radioactivity and gamma-ray exposure in the United States and Canada
AU  - Joseph S. Duval
AU  - John M. Carson
AU  - Peter B. Holman
AU  - Arthur G. Darnley
PY  - 2005
DO  - 10.3133/ofr20051413
UR  - https://pubs.usgs.gov/publication/ofr20051413
ID  - ofr20051413
ER  -