@article{DAN_1989_306_4_a15,
     author = {E. M. Vorob'ev and N. V. Ignatovich and E. O. Semenova},
     title = {Invariant and partially invariant solutions of boundary value},
     journal = {Doklady Akademii Nauk},
     pages = {836--840},
     publisher = {mathdoc},
     volume = {306},
     number = {4},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_306_4_a15/}
}