@article{DE_1991_27_9_a9,
     author = {I. S. Lomov},
     title = {A theorem on the unconditional basis property of root vectors of second-order weighted differential operators},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1550--1563},
     publisher = {mathdoc},
     volume = {27},
     number = {9},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_9_a9/}
}