Stiglic, Paul M. & Heppler, Herbert. Experimental investigation of an overriding control to effect recovery from surge and stall in a turbojet engine, report, October 29, 1956; (https://digital.library.unt.edu/ark:/67531/metadc63159/m1/1/: accessed November 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .