@article{MS2_1994__75_2_167306,
     author = {O. Martio and Li Gongbao},
     title = {Stability in {Obstacle} {Problems.}},
     journal = {Mathematica Scandinavica},
     pages = {87--100},
     publisher = {mathdoc},
     volume = {75},
     number = {2},
     year = {1994},
     zbl = {0839.35050},
     url = {http://geodesic.mathdoc.fr/item/MS2_1994__75_2_167306/}
}