The present state of physics; a symposium presented on December 30, 1949, at the New York meeting of the American Association for the Advancement of Science, arr. by Frederick S. Brackett. American Association for the Advancement of Science. Brackett, Frederick Sumner, 1896- Physics. QC71 .A55 1949 530.4 19 AMP Includes bibliographies. Washington, 1954. 1954. 1954 Text vi, 265 p. eng