1. G. Fichera, Sul problema elastostatico di Signorini con ambigue condizioni al contorno. Rendiconti della Accademia Nazionale dei Lincei, Classe di Scienze Fisiche, Matematiche e Naturali 834(2), 138–142 (1963)
2. G. Duvaut, J.-L. Lions, Les in
$$\acute{e}$$
quations en m
$$\acute{e}$$
canique et en physique (Dunod, Paris, 1972)
3. D. Kinderlehrer, G. Stampacchia, An Introduction to Variational Inequalities and Their Applications (Academic, New York, 1980)
4. R. Glowinski, J.-L. Lions, R. Tr
$$\acute{e}$$
molier, Numerical Analysis of Variational Inequalities (North Holland, Amsterdam, 1981)
5. C. Baiocchi, A. Capelo, Variational and Quasivariational Inequalities: Applications to Free-Boundary Problems (Wiley, New York, 1984)