@article{MZM_1977_22_3_a5,
     author = {V. P. Kondrat'ev},
     title = {Some extremal properties of positive trigonometric polynomials},
     journal = {Matemati\v{c}eskie zametki},
     pages = {371--374},
     publisher = {mathdoc},
     volume = {22},
     number = {3},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1977_22_3_a5/}
}