@article{RM_1963_18_3_a19,
     author = {G. I. \`Eskin},
     title = {General boundary-value problems for equations of principal type in a~planar domain with angle points},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {18},
     number = {3},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1963_18_3_a19/}
}