@article{ISU_2011_11_4_a6,
     author = {V. S. Rykhlov and O. V. Parfilova},
     title = {On multiple completeness of the root functions of the pencils of differential operators with constant coefficients},
     journal = {Izvestiya of Saratov University. Mathematics. Mechanics. Informatics},
     pages = {45--58},
     publisher = {mathdoc},
     volume = {11},
     number = {4},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ISU_2011_11_4_a6/}
}