@article{SM_1976_28_4_a1,
     author = {A. M. Il'in},
     title = {A~boundary value problem for the elliptic equation of second order in a~domain with a~narrow slit. {1.~The} two-dimensional case},
     journal = {Sbornik. Mathematics},
     pages = {459--480},
     publisher = {mathdoc},
     volume = {28},
     number = {4},
     year = {1976},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1976_28_4_a1/}
}