[1] K. Washizu: Variational methods in elasticity and plasticity. Pergamon Press, 1968. MR 0391679 | Zbl 0164.26001

[2] J. Kratochvíl O. W. Dillon: Thermodynamics of Elastic-Plastic Materials as a Theory with Internal State Variables. J. Applied Physics, Vol. 40, n. 8, 3207-3218, 1969.

[3] J. Nečas: Les méthodes directes en théorie des équations elliptiques. Academia, Prague 1967. MR 0227584

[4] I. Hlaváček J. Nečas: On Inequalities of Korn's Type. Archive for Rat. Mech. Anal. Vol. 36, No. 4, 1970, 305-311, 312-334.