@article {1989, title = {A pointwise regularity theory for the two-obstacle problem}, journal = {Acta Math. 163 (1989), no. 1-2, 57-107}, number = {SISSA;47/88/M}, year = {1989}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/643}, author = {Gianni Dal Maso and Umberto Mosco and Maria Agostina Vivaldi} }