@article{TIMM_1992_2_a6,
     author = {T. V. Elina},
     title = {The best approximation of convolution-type operator on the class of doubly differentiable functions},
     journal = {Trudy Instituta matematiki i mehaniki},
     pages = {70--78},
     publisher = {mathdoc},
     volume = {2},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMM_1992_2_a6/}
}