1. Badie A. “Stability of Spread Footing Supported by Clay with an Underground Void ” thesis presented to The Pennsylvania State University at University Park Pa. in 1982 in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
2. Stability of Spread Footing Above Void in Clay
3. Baus R. L. “The Stability of Shallow Continuous Footings Located above Voids ” thesis presented to The Pennsylvania State University at University Park Pa. in 1980 in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
4. Bearing Capacity of Strip Footing above Void
5. Chen W. F. “Limit Analysis and Soil Plasticity ” Elsevier Scientific New York N.Y. 1974.