@article{SM_1997_188_1_a6,
     author = {S. A. Stepin},
     title = {Non-selfadjoint singular perturbations and spectral properties of {the~Orr--Sommerfeld} boundary-value problem},
     journal = {Sbornik. Mathematics},
     pages = {137--156},
     publisher = {mathdoc},
     volume = {188},
     number = {1},
     year = {1997},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1997_188_1_a6/}
}