@article{MABA_1988_2_2_a14,
     author = {Liudmil Alexandrov. Vasil Popov},
     title = {Onesided {Trigonometrical} {Approximation} of {Periodic} {Multivariate} {Functions}},
     journal = {Mathematica balkanica},
     pages = {230},
     publisher = {mathdoc},
     volume = {2},
     number = {2},
     year = {1988},
     url = {http://geodesic.mathdoc.fr/item/MABA_1988_2_2_a14/}
}