1. Chen W. S. (1975). Limit analysis and soil plasticity . Elsevier Science Publishing Co. Amsterdam The Netherlands 447–491.
2. Japanese Society of Soil Mechanics and Foundation Engineering. (1990). “Test method for maximum and minimum densities of sands.” Rep.; Soil testing methods and their explanations Tokyo Japan 106–115 (in Japanese).
3. Roark R. J. and Young W. C. (1975). Formulas for stress and strain 5th Ed. McGraw‐Hill Kogakusha Ltd. 503–508.