@article{DE_1987_23_5_a26,
     author = {Yu. K. Lando and S. V. Yashchuk},
     title = {On conditionally solvable integro-differential operators},
     journal = {Differencialʹnye uravneni\^a},
     pages = {902--904},
     year = {1987},
     volume = {23},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_5_a26/}
}