@article{SM_1967_3_3_a0,
     author = {M. I. Vishik and G. I. \`Eskin},
     title = {Normally solvable problems for elliptic systems of equations in convolutions},
     journal = {Sbornik. Mathematics},
     pages = {303--332},
     year = {1967},
     volume = {3},
     number = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1967_3_3_a0/}
}