@article{DAN_1970_192_4_a5,
     author = {V. B. Lidskii and P. A. Frolov},
     title = {Connectivity components of normally solvable elliptic systems on the plane},
     journal = {Doklady Akademii Nauk},
     pages = {728--731},
     publisher = {mathdoc},
     volume = {192},
     number = {4},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1970_192_4_a5/}
}