@article{DE_1973_9_12_a14,
     author = {Yu. K. Lando},
     title = {Controllable integro-differential operators},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2227--2230},
     publisher = {mathdoc},
     volume = {9},
     number = {12},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_12_a14/}
}