@article{10_1017_S001708950000080X,
     author = {Cohen, Stephen D.},
     title = {Some arithmetical functions in finite fields},
     journal = {Glasgow mathematical journal},
     pages = {21--36},
     year = {1970},
     volume = {11},
     number = {1},
     doi = {10.1017/S001708950000080X},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S001708950000080X/}
}