@article{AA_2016_28_6_a1,
     author = {V. E. Ismailov},
     title = {Approximation by sums of ridge functions with fixed directions},
     journal = {Algebra i analiz},
     pages = {20--69},
     publisher = {mathdoc},
     volume = {28},
     number = {6},
     year = {2016},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2016_28_6_a1/}
}