@article{AA_1992_4_4_a1,
     author = {Yu. A. Brudnyi and I. P. Irodova},
     title = {Nonlinear spline approximation of functions of several variables and $B$-spaces},
     journal = {Algebra i analiz},
     pages = {45--79},
     publisher = {mathdoc},
     volume = {4},
     number = {4},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_1992_4_4_a1/}
}