@article{IVM_1968_5_a0,
     author = {L. M. Berkovich and V. I. Kval'vasser},
     title = {Operator identities and certain ordinary linear differential equations of higher orders which are integrable in closed form},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {3--16},
     publisher = {mathdoc},
     number = {5},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1968_5_a0/}
}