@article{DE_1968_4_8_a9,
     author = {V. V. Ryndina},
     title = {A transformation operator for a sequence of solutions of a certain class of second order linear differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1441--1451},
     publisher = {mathdoc},
     volume = {4},
     number = {8},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_8_a9/}
}