@article{IM2_1986_27_2_a5,
     author = {V. N. Temlyakov},
     title = {Approximation of periodic functions of several variables by trigonometric polynomials, and widths of some classes of functions},
     journal = {Izvestiya. Mathematics },
     pages = {285--322},
     publisher = {mathdoc},
     volume = {27},
     number = {2},
     year = {1986},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1986_27_2_a5/}
}