@article{DAN_1991_317_5_a2,
     author = {A. Dzhuraev},
     title = {First-order elliptic systems that are degenerate on the boundary},
     journal = {Doklady Akademii Nauk},
     pages = {1041--1045},
     year = {1991},
     volume = {317},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_317_5_a2/}
}