@article{IM2_1987_28_1_a6,
     author = {V. N. Temlyakov},
     title = {Approximation of periodic functions of several variables by bilinear forms},
     journal = {Izvestiya. Mathematics },
     pages = {133--150},
     publisher = {mathdoc},
     volume = {28},
     number = {1},
     year = {1987},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1987_28_1_a6/}
}