@article{DAN_1977_232_6_a0,
     author = {B. D. Boyanov},
     title = {Characterization and existence of optimal quadrature formulas for a class of differentiable functions},
     journal = {Doklady Akademii Nauk},
     pages = {1233--1236},
     publisher = {mathdoc},
     volume = {232},
     number = {6},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_232_6_a0/}
}