@article{MABA_1990_4_3-4_a2,
     author = {V. H. Hristov and K. G. Ivanov},
     title = {Realization of {K-Functionals} on {Subsets} and {Constrained} {Approximation}},
     journal = {Mathematica balkanica},
     pages = {236},
     year = {1990},
     volume = {4},
     number = {3-4},
     url = {http://geodesic.mathdoc.fr/item/MABA_1990_4_3-4_a2/}
}