1. Soil density determination by direct transmission of gamma rays;Bernhard,1955
2. GRAPE—A device for continuous determination of material density and porosity;Evans,1965
3. X-ray attenuation coefficients from 10 keV to 100 MeV;Grodstein;Circ. U.S. natn. Bur. Stand.,1957
4. Geologic evaluation of a gamma-ray porosity device;Harms,1965
5. Radioisotope Applications Engineering;Kohl,1961