@article{IM2_1972_6_1_a6,
     author = {L. D. Ivanov},
     title = {On approximation of $l$-smooth functions by rational functions in the integral metric},
     journal = {Izvestiya. Mathematics },
     pages = {235--240},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1972},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1972_6_1_a6/}
}