@article{MZM_2009_85_4_a4,
     author = {V. F. Babenko and N. V. Parfinovich},
     title = {Exact {Values} of {Best} {Approximations} for {Classes} of {Periodic} {Functions} by {Splines} of {Deficiency~2}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {538--551},
     publisher = {mathdoc},
     volume = {85},
     number = {4},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2009_85_4_a4/}
}