@article{TRSPY_1976_142_a9,
     author = {V. A. Il'in},
     title = {Existence of a~reduced system of eigen- and associated functions for a~nonselfadjoint ordinary differential operator},
     journal = {Informatics and Automation},
     pages = {148--155},
     publisher = {mathdoc},
     volume = {142},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1976_142_a9/}
}