@article{SM_1992_73_1_a9,
     author = {A. K. Gushchin and V. P. Mikhailov},
     title = {On~the existence of boundary values of solutions of an elliptic equation},
     journal = {Sbornik. Mathematics},
     pages = {171--194},
     year = {1992},
     volume = {73},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1992_73_1_a9/}
}