1. BASIS FOR DERIVATION OF MATRICES FOR THE DIRECT STIFFNESS METHOD
2. The complete analogy between the matrix equations and the continuous field equations of structural analysis;Besseling,1963
3. Displacement and equilibrium models in the finite element method;De Veubeke,1965
4. The Hypercircle in Mathematical Physics;Synge,1967
5. Y. C. Fung,Foundations of Solid Mechanics, chapter 10. Prentice-Hall.