Physics for Radiation Protection and Permissible Dose: A History of Radiation Protection in the Twentieth Century Physics for Radiation Protection , James E. Martin , Wiley, New York, 2000. $150.00 (713 pp.). ISBN 0-471-35373-6Permissible Dose: A History of Radiation Protection in the Twentieth Century, J. Samuel Walker , U. of California Press, Los Angeles, 2000. $35.00 (180 pp.). ISBN 0-520-22328-4