[1] J. Haslinger I. Hlaváček: 
Convergence of a finite element method based on the dual variational formulation. Apl. mat. 21 (1976), 43 - 65. 
MR 0398126 
[2] B. Fraeijs de  Veubeke M. Hogge: Dual analysis for heat  conduction problems by finite elements. Inter. J. Numer. Meth. Eng. 5 (1972), 65 - 82.
[3] V. B. Watwood, Jr. B. J. Hartz: An equilibrium stress field model for finite element solutions of two-dimensional elastostatic problems. Inter. J. Solids and Struct. 4 (1968), 857-873.
[4] I. Hlaváček: 
Variational principles in the linear theory of elasticity for general boundary conditions. Apl. mat. 12 (1967), 425-448. 
MR 0231575 
[5] G. Sander: Application of the dual analysis principle. Proc. of IUTAM Symp. on High Speed Computing of Elastic Structures, 167-207, Univ. de Liege, 1971 (ruský překlad - izdat. Sudostrojenije, Leningrad 1974).
[6] B. Fraeijs de Veubeke: Finite elements method in aerospace engineering problems. Proc. of Inter. Symp. Computing Methods in Appl. Sci. and Eng., Versailles, 1973, Part 1, 224-258.
[7] J. Nečas: 
Les méthodes directes en théorie des équations elliptiques. Academia, Prague, 1967. 
MR 0227584 
[8] C. Johnson B. Mercier: 
Some equilibrium finite element methods for two-dimensional elasticity problems. Numer. Math. 30, (1978), 103-116. 
DOI 10.1007/BF01403910 | 
MR 0483904