@article{DE_1973_9_5_a20, author = {G. A. Kalyabin}, title = {A necessary and sufficient condition for the discreteness of the spectrum of a monomial operation in the matrix case}, journal = {Differencialʹnye uravneni\^a}, pages = {951--954}, publisher = {mathdoc}, volume = {9}, number = {5}, year = {1973}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1973_9_5_a20/} }