Wu, S Q & Hartemann, F V. Transient evolution of a photon gas in the nonlinear QED vacuum, report, October 4, 2011; (https://digital.library.unt.edu/ark:/67531/metadc834710/m1/1/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .