@article{CMUC_1971__12_4_a3,
     author = {Nov\'ak, B\v{r}etislav},
     title = {On certain sum in number theory},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {669--685},
     publisher = {mathdoc},
     volume = {12},
     number = {4},
     year = {1971},
     mrnumber = {0308054},
     zbl = {0234.10029},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1971__12_4_a3/}
}