@article{DAN_1993_331_5_a8,
     author = {S. I. Trifonov},
     title = {Analytic families of differential equations on two-dimensional},
     journal = {Doklady Akademii Nauk},
     pages = {559--562},
     publisher = {mathdoc},
     volume = {331},
     number = {5},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1993_331_5_a8/}
}