Bern, Zvi; Dixon, Lance J. & Kosower, David A. The Last of the Finite Loop Amplitudes in QCD, article, May 31, 2005; (https://digital.library.unt.edu/ark:/67531/metadc873114/m1/1/: accessed November 12, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .