@article{RM_1978_33_5_a20,
     author = {\`E. Z. Shuvalova},
     title = {The construction of~an~element of~best approximation to~a~derivative},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {207--208},
     publisher = {mathdoc},
     volume = {33},
     number = {5},
     year = {1978},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1978_33_5_a20/}
}