XI. References Cited
 1. Bartolomew, R. N., and R. M. Casagrande. 1957. Measuring solids con-
 centration in fluid systems by gamma-ray absorption. Ind. Eng. Chem. 49
 (30):428-431.
 2. Belcher, D. J., T. R. Cuykendall, and H. S. Sack. 1950. The measurement
 of soil moisture and density by neutron and gamma ray scattering. Technical
 Development Report no. 127, Civil Aeronautics Administration, Washington,
 SD.C.
 3. Berman, A. I., and J. N. Harris. 1954. Precision measurement of unifor-
 mity of materials by gamm ray transmission. Rev. Sci. Inst. 25:21-19.
 4. Bernhard, R. K., and M. Chasek. 1955. Soil density determination by direct
 transmission of gamma ray. American Society for Testing Materials, Phila-
 delphia, Pa., Preprint No. 86.
 5. Bridge, B. J., and N. Collis-George. 1973. A dual source gamma ray travers-
 ing mechanism suitable for the nondestructive simultaneous measurement of
 bulk density and water content in columns of swelling soil. Aust. J. Soil Res.
 11:83-92.
 6. Chase, G. D., and J. L. Rabinowitz. 1968. Principles of radioisotope meth-
 odology. Burgess Publishing Co., Minneapolis, Minn., pp. 38-42.
 7. Christensen, E. R. 1974. Use of the gamma density gauge in combination
 with the neutron moisture probe. In "Isotope and radiation techniques in soil
 physics and irrigation studies 1973." International Atomic Energy Association
 Report SM-176/1, pp. 27-44.
 8. Cisler, J., J. L. Thony, and G. Vachaud. 1969. Mesures des teneurs in eau
 d'echantillons de sol non satures par attenuation du rayonnement emis par une
 source d'americium 241. C. R. Acad. Sci. Paris 269:982-985.
 9. Conner, A. L., H. F. Atwater, E. H. Plassmann, and J. H. McCrary. 1970.
 Gamma-ray attenuation coefficients measurements. Phys. Rev. 1(3):539-544.
10. Coppola, M., and P. Reiniger. 1974. Influence of the chemical composition
 on the gamma-ray attenuation by soils. Soil Sci. 117(6):331-335.
11. Corey, J. C., R. H. Hawkins, R. F. Overman, and R. E. Green. 1970. Mis-
 cible displacement measurements within laboratory columns using the gamma-
 photoneutron method. Soil Sci. Soc. Amer. Proc. 34:854-858.
12. Corey, J. C., R. H. Hawkins, and R. F. Overman. 1970. A gamma-photo-
 neutron method for laboratory studies of soil water. Soil Sci. Soc. Amer. Proc.
 34:557-560.
13. Corey, J. C., S. F. Peterson, and M. A. Wakat. 1971. Measurement of at-
 tenuation of 137Cs and 241Am gamma rays for soil density and water content
 determinations. Soil Sci. Soc. Amer. Proc. 35:215-219.
14. Covell, D. F., and B. A. Euler. 1961. Gain shift versus counting rate in
 certain multiplier phototubes. Proceedings of 1961 International Conference:
 "Modern trends in activation analysis" held December 15-16, 1961 at College
 Station, Texas, pp. 12-15.
15. Crouthanel, C. E. 1960. Applied gamma-ray spectrometry. New York.
 Pergamon Press.
16. Cusimano, J. P. 1967. Field experience with thermoluminescent dosimeters.
 United States Atomic Energy Commission Report, 1DO-12004.
17. Davidson, J. M., J. W. Biggar, and D. R. Nielsen. 1963. Gamma radiation
 attenuation for measuring bulk density and transient water flow in porous
 materials. J. Geophys. Res. 68(16):4777-4783.
18. Davisson, C. M., and R. D. Evans. 1951. Measurements of gamma ray
 absorption coefficients. Phys. Rev. 81:404-409.
19. Davisson, C. M. 1955. Interaction of -y-radiation with matter. In Siegbahn,
 ed. Beta and gamma-ray spectroscopy. Amsterdam, North-Holland, 24-51.
20. Denmead, 0. T., and R. H. Shaw. 1962. Availability of soil water to plants
 as affected by soil moisture content and meteorological conditions. Agron. J.
 54:385-390.