@article{CMUC_1972_13_4_a13,
     author = {Nov\'ak, B\v{r}etislav},
     title = {On a certain sum in number theory. {III}},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {763--775},
     year = {1972},
     volume = {13},
     number = {4},
     mrnumber = {0330081},
     zbl = {0285.10024},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1972_13_4_a13/}
}