Yntema, Robert T & Milwitzky, Benjamin. An Impulse-Momentum Method for Calculating Landing-Gear Contact Conditions in Eccentric Landings, report, January 1, 1952; (https://digital.library.unt.edu/ark:/67531/metadc56236/m1/1/: accessed July 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .