@article{SM_1976_30_3_a4,
     author = {B. V. Fedosov},
     title = {An analytic formula for the index of an elliptic boundary value {problem.~III}},
     journal = {Sbornik. Mathematics},
     pages = {341--359},
     publisher = {mathdoc},
     volume = {30},
     number = {3},
     year = {1976},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1976_30_3_a4/}
}