1. M. M. Vainberg,Variational methods for the study of nonlinear operators, Holden-Day, 1964.
2. V. V. Bolotin,Nonconservative problems of the theory of elastic stability, Pergamon Press, 1963.
3. C. E. Pearson,General theory of elastic stability, Quart. Appl. Math.14, 133, 1956.
4. I. S. Sokolnikoff,Tensor analysis, II Ed., Wiley, 1967.
5. D. C. Leigh,Nonlinear continuum mechanics, McGraw-Hill, 1968.