@article{IVM_1969_11_a3,
     author = {I. Ya. Guberman},
     title = {The differentiability of continuous functions which satisfy certain functional relations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {37--43},
     publisher = {mathdoc},
     number = {11},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1969_11_a3/}
}