1. Off road locomotion;Bekker,1960
2. A dimensional analysis of the performance of pneumatic tires on soft soils;Freitag;USAE Waterways Experiment Station Techn. Rept. No. 3–688,1965
3. Feasibility of model study in earthworking equipment;Schuring;Trans. ASAE,1965
4. Some physical properties of sands used in mobility studies;Littleton,1977
5. An investigation into rolling resistance theories for towed rigid wheels;Wills;J. Terramechanics,1965