00603mas a22001571 4500 880509d19611963nyuuu 0 0eng d Lectures in theoretical physics. Edited by Wesley E., B. W . Downs and Joanne Downs. New York, Interscience Publishers. [625 p.] ill. Volume IV lectures delivered at the summer institute for theoretical physics, University of Colorado, Boulder, 1961.. Mathematical physics. 2291 Brittin, Wesley E. 9794 Downs, B. W. 9795 Downs, Joanne. 9796 BK 30950 30950