Terrestrial radioactivity and gamma-ray exposure in the United States and Canada

Online link http://pubs.usgs.gov/of/2005/1413/
Description Flight-line databases and derived grids from aeroradiometric surveys across the US carried out during the 1970s
Originators Duval, Joseph S.; Carson, John M.; Holman, Peter B.; and Darnley, Arthur G.
Publication U.S. Geological Survey Open-File Report 2005-1413