@article{DAN_1963_152_3_a13,
     author = {S. G. Mikhlin},
     title = {On the index of a system of singular equations},
     journal = {Doklady Akademii Nauk},
     pages = {555--558},
     publisher = {mathdoc},
     volume = {152},
     number = {3},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_152_3_a13/}
}