@article{FAA_1970_4_4_a5,
     author = {B. V. Fedosov},
     title = {Index of an elliptic system on a manifold},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {57--67},
     publisher = {mathdoc},
     volume = {4},
     number = {4},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1970_4_4_a5/}
}