@article{oai:tsukuba.repo.nii.ac.jp:00016022,
 author = {Grytczuk, Aleksander},
 issue = {2},
 journal = {Tsukuba Journal of Mathematics},
 month = {Dec},
 pages = {315--319},
 title = {On Ramanujan sums on arithmetical semigroups},
 volume = {16},
 year = {1992}
}