@article{IVM_1983_5_a13, author = {M. A. Zaretskaya}, title = {The spectrum of a~class of differential operators}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {76--78}, publisher = {mathdoc}, number = {5}, year = {1983}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1983_5_a13/} }