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@article{DE_2006_42_6_a0, author = {A. I. Vagabov and Z. A. Abdurakhmanov}, title = {Conditions for the $k$-fold completeness ($0<k\le n$) of root functions of an $n$th-order ordinary differential operator pencil}, journal = {Differencialʹnye uravneni\^a}, pages = {723--730}, publisher = {mathdoc}, volume = {42}, number = {6}, year = {2006}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_2006_42_6_a0/} }
A. I. Vagabov; Z. A. Abdurakhmanov. Conditions for the $k$-fold completeness ($0