@article{ZNSL_1997_240_a15,
     author = {N. A. Sidorov},
     title = {Sum-of-digits function for certain non-stationary bases},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {257--267},
     year = {1997},
     volume = {240},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1997_240_a15/}
}