@article{AFM_1994_19_1_a2,
     author = {Gongbao Li and Olli Martio},
     title = {Local and global integrability of gradients in obstacle problems},
     journal = {Annales Fennici Mathematici},
     pages = {25--34},
     publisher = {mathdoc},
     volume = {19},
     number = {1},
     year = {1994},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AFM_1994_19_1_a2/}
}