@article{DAN_1980_254_1_a3,
     author = {P. B. Gusyatnikov and E. S. Polovinkin},
     title = {On two types of operators for biparametric equations},
     journal = {Doklady Akademii Nauk},
     pages = {20--24},
     publisher = {mathdoc},
     volume = {254},
     number = {1},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1980_254_1_a3/}
}