@article{ASNSP_1979_4_6_1_151_0, author = {Caffarelli, Luis A. and Friedman, Avner}, title = {The obstacle problem for the biharmonic operator}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze}, pages = {151--184}, publisher = {Scuola normale superiore}, volume = {Ser. 4, 6}, number = {1}, year = {1979}, zbl = {0405.31007}, mrnumber = {529478}, language = {en}, url = {http://www.numdam.org/item/ASNSP_1979_4_6_1_151_0/} }