@article{SM_1991_68_1_a11,
     author = {Nguy\^en Thị Thi\^eu Hoa},
     title = {Some extremal problems on classes of functions determined by linear differential operators},
     journal = {Sbornik. Mathematics},
     pages = {213--255},
     publisher = {mathdoc},
     volume = {68},
     number = {1},
     year = {1991},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1991_68_1_a11/}
}