1. Axtell, P.J. (2001). "In-Situ Measurements of Linear and Nonlinear Properties of a Near-Surface, Poorly Graded Sand". Master's Thesis, University of Texas at Austin.
2. Stokoe, II, K.H., Axtell, P.J. and Rathje, E.M. (2001). "Development of an In Situ Method to Measure Nonlinear Soil Behavior" Proc. Third International Conference on Earthquake Resistant Engineering Structures, Malaga, Spain.