@article{TRSPY_1966_92_a12,
     author = {A. P. Oskolkov},
     title = {Prior estimates of the first derivatives for two-dimensional quasi-linear strongly elliptic systems},
     journal = {Informatics and Automation},
     pages = {192--202},
     publisher = {mathdoc},
     volume = {92},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1966_92_a12/}
}