Johnson, Joseph L. A Theoretical Investigation of the Dynamic Lateral Oscillatory Stability of an Airplane Having a 60 Degree Triangular Wing, report, March 8, 1950; (https://digital.library.unt.edu/ark:/67531/metadc58196/m1/1/: accessed December 14, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .