@article{DAN_1987_295_6_a6,
     author = {Nguyen Thi Thien Hoa},
     title = {Rolle's theorem for differential operators, and some extremal},
     journal = {Doklady Akademii Nauk},
     pages = {1313--1318},
     publisher = {mathdoc},
     volume = {295},
     number = {6},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_295_6_a6/}
}