@article{MABA_1997_11_1-2_a4,
     author = {P. E. Parvanov},
     title = {A {Characterization} of {Best} {Multivariate} {Algebraic} {Approximations} from {Below} and from {Above} in {Terms} of {K-Functionals}},
     journal = {Mathematica balkanica},
     pages = {37},
     publisher = {mathdoc},
     volume = {11},
     number = {1-2},
     year = {1997},
     url = {http://geodesic.mathdoc.fr/item/MABA_1997_11_1-2_a4/}
}