@article{IVM_2009_11_a5,
     author = {Yu. N. Subbotin},
     title = {Form-preserving exponential approximation},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {53--60},
     publisher = {mathdoc},
     number = {11},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2009_11_a5/}
}