@article{DAN_1969_189_3_a7,
     author = {A. I. Perov and T. K. Katsaran},
     title = {Nonlinear multidimensional differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {479--482},
     publisher = {mathdoc},
     volume = {189},
     number = {3},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_189_3_a7/}
}