Barber, W. C.; Richter, B.; Panofsky, W. K. H.; O'Neill, G. K. & Gittelman, B. An Experiment on the Limits of Quantum Electro-Dynamics, report, June 1, 1959; (https://digital.library.unt.edu/ark:/67531/metadc865960/m1/2/: accessed November 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .