@article{SM_1988_61_1_a9,
     author = {S. A. Ivanov},
     title = {Best approximations by rational vector-valued functions in {Hardy} spaces},
     journal = {Sbornik. Mathematics},
     pages = {137--145},
     publisher = {mathdoc},
     volume = {61},
     number = {1},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1988_61_1_a9/}
}