1. Y. C. Fung,Foundation of Solid Mechanics, Prentice Hall, 1965.
2. E. Reissner,On a Variational Theorem in Elasticity, J. Math. and Phys. 29, pp. 90–95, 1950.
3. B. Fraeys de Veubeke, Bull. Service Techn. Acronaut. no. 24, Bruxelles, 1951.
4. C. Lanczos,The Variational Principles of Mechanics, University of Toronto Press, 1952.
5. Hay-Chang Hu,On Some Variational Principles in the Theory of Elasticity and Plasticity, Scientia Sinica, Vol. IV, pp. 33–55, 1955.