@article{M2AN_1975__9_2_5_0,
     author = {Falk, Richard S.},
     title = {Approximation of an elliptic boundary value problem with unilateral constraints},
     journal = {ESAIM: Mathematical Modelling and Numerical Analysis },
     pages = {5--12},
     publisher = {Dunod},
     address = {Paris},
     volume = {9},
     number = {R2},
     year = {1975},
     mrnumber = {390477},
     zbl = {0316.65024},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/M2AN_1975__9_2_5_0/}
}