@article{GDZPPN001174630,
title = {Error Estimates for the Finite Element Solution of Variational Inequalities. Part II. Mixed Methods.},
journal = {Numerische Mathematik},
volume = {30},
year = {1978},
pages = {1-16},
zbl = {0427.65077},
url = {http://dml.mathdoc.fr/item/GDZPPN001174630}
}
Brezzi, F.; Hager, W.W.; Raviart, P.A. Error Estimates for the Finite Element Solution of Variational Inequalities. Part II. Mixed Methods.. Numerische Mathematik, Tome 30 (1978) pp. 1-16. http://gdmltest.u-ga.fr/item/GDZPPN001174630/