@article{MZM_1997_62_3_a14,
     author = {A. D. Valiev and A. S. Demidov},
     title = {Nonnegative trigonometric polynomials with fixed mean passing through given points},
     journal = {Matemati\v{c}eskie zametki},
     pages = {468--471},
     publisher = {mathdoc},
     volume = {62},
     number = {3},
     year = {1997},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1997_62_3_a14/}
}