@article{DAN_1977_236_1_a0,
     author = {M. A. Valiev and S. A. Lomov},
     title = {A general approach to the asymptotic integration of singularly perturbed problems in the case of an unbounded nonselfadjoint operator},
     journal = {Doklady Akademii Nauk},
     pages = {11--13},
     year = {1977},
     volume = {236},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_236_1_a0/}
}