@article{KUIPM_1992_19_19_a9,
     author = {V. S. Mokeichev},
     title = {Perturbation theory in a nonselfadjoint special case},
     journal = {Issledovaniya po Prikladnoi Matematike i Informatike},
     pages = {81--89},
     year = {1992},
     volume = {19},
     number = {19},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/KUIPM_1992_19_19_a9/}
}