20. S. M. Greenfield, Rain Scavenging of Radioactive Particulate Matter from the Atmosphere, J. Meteorol. 14, 115-25 (1957). 21. Haro von Buttlar and W. F. Libby, Natural Distribution of Cosmic Ray Produced Tritium Il, J. Inorg. & Nuclear Chem, 1, 15 (1955). 22. N. G. Stewart, R. N. Crooks, and E. M. R. Fisher, The Radiological Dose to Persons in the U.K. Due to Debris from Nuclear Test Explosions, AERE HP/R 1701, (1955). 23. W.R. Collins and N. A. Haliden, A Study of Fallout in Rainfall Collections from March through July 1956, April 30, 1957, NYO-4839. J. H. Harley, E. P. Hardy, Jr., G. A. Welford, I. B. Whitney, M. Eisenbud, Summary of Analytical Results from the HASL Strontium Program to June 1956, August 31, 1956, NYO-4751. J. H. Harley, E. P. Hardy, Jr., I. B. Whitney, and M. Eisenbud, Summary of Analytical Results from the HASL Strontium Pro- gram July through December 1956, NYO-4862. 24. W. F. Neuman and Margaret W. Neuman, Chemical Dynamics of Bone Mineral, Monograph, University of Chicago Press (1958). 25. I. Ogawa, Fallout and Rice Contamination in Japan, Bull. Atomic Scientists 14, 35 (1958). 26. L. P. Solon, W. M. Lowder, A. V. Zila, H. D. LeVine, H. Blatz, and M. Eisenbud, External Radiation Measurements in the United States, Science (In press). 27. P.R. J. Burch, Proc. Phys. Soc., 671A 421 (1954). 28. H. V. Neher, Gamma Rays from Local Radioactive Sources, Science 125, 3257 (1957). 29. The Biological Effects of Atomic Radiation, National Academy of Sciences (1956). 30. B. P. Sonnenblick, Aspects of Genetic and Somatic Risk in Diagnostic Roentgenology, Jour. of Newark Beth Israel Hosp., Newark, N. J. VU, 2, 81 (1957). 31. G. J. Fergusson, Reduction of Atmospheric Radiocarbon Concentration by Fossil Fuel Carbon Dioxide and the Mean Life of Carbon Dioxide in the Atmosphere, Proc. Royal Soc. (London), Series A 243, 561-74 (1958). 32. H. E. Suess, Radiocarbon Concentration in Modern Wood, Science 122, 415 (1955). 33. H. Craig, Natural Distribution of Radiocarbon and the Exchange Time of CO, between Atmosphere and Sea, Tellus 9, 1 (1957). 34. R. Revelle and H. E. Suess, Carbon Dioxide Exchange between Atmosphere and Ocean, and the Question of an Increase of Atmospheric CO, during the Past Decades, Telius 9, 18 (1957). 35, J.R. Arnold and E. C. Anderson, The Distribution of Carbon-14 in Nature, Tellus 9, 28 (1957). 36. T. A. Rafter and G. J. Fergusson, Atom Bomb Effect-——Recent Increase of Carbon-14 Content of the Atmosphere and Biosphere, Science 126, 557,(1957). 37. T.A. Rafter, New Zealand J. Sci, Technol, B37, 20 (1955); 18, 871 (1957). 38. M. Williams, private communication. 39. N. G. Stewart, R. G. D. Osmond, R. N. Crooks, E. M. R. Fisher, The World-wide Deposition of Long-Lived Fission Products from Nuclear Test Explosions, AERE HP/R 2354, (1957). 40. Geochemistry, Rankama and Sahama, University of Chicago Press (1950). 41. L. Machta, Indianapolis Meeting, AAAS, December 1957 (In press). 42. H. de Vries, Atom Bomb Effect. The Natural Activity of Radiocarbon in Plants, Shells, 43. 44. 45. 46. 47. and Snails in the Past Four Years, Science (In press). K. O. Munnich, private communication. W. F. Libby, Radioactive Fallout and Radioactive Strontium, Science 123, 657 (1956). W. F. Libby, Radiocarbon Dating, University of Chicago Press (1955), 2nd ed. S. Kaufman and W. F. Libby, Natural Distribution of Tritium, Phys. Rev. 93, 1337 (1954). F. Begemann and W. F. Libby, Continental Water Balance, Ground Water Inventory and Storage Times, Surface Ocean Mixing Rates and World-wide Water Circulation Patterns from Cosmic-ray and Bomb Tritium, Geochim. et Cosmochim, Acta, 12, 277-96 (1957). 267