@article{MZM_1991_50_5_a9,
     author = {A. V. Reztsov},
     title = {Nonnegative trigonometric polynomials in many variables and cubature formulas of {Gaussian} type},
     journal = {Matemati\v{c}eskie zametki},
     pages = {69--74},
     year = {1991},
     volume = {50},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_50_5_a9/}
}