@article{IVM_1970_12_a2,
     author = {G. P. Gubanov},
     title = {Approximations of functions by trigonometric polynomials of the best (quadratic) approximation},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {22--29},
     publisher = {mathdoc},
     number = {12},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1970_12_a2/}
}