@article{DAN_1978_240_4_a7,
     author = {R. S. Saks},
     title = {Weakly elliptic systems of pseudodifferential equations on a manifold without boundary},
     journal = {Doklady Akademii Nauk},
     pages = {786--789},
     publisher = {mathdoc},
     volume = {240},
     number = {4},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_240_4_a7/}
}