Feynman's proper time approach to QED
  The genesis of Feynman's original approach to QED is reviewed. The main ideas of his original presentation at the Pocono Conference are discussed and compared with the ones involved in his action-at-distance formulation of classical electrodynamics. The role of the de Sitter group in Feynman's visualization of space-time processes is pointed out. 
Edgardo T. Garcia Alvarez and Fabian H. Gaioli