@article{2712,
author = {Shader, Leslie E.},
title = {Closed form expressions for several Ramanujan sums},
journal = {Portugaliae mathematica},
volume = {32},
year = {1973},
pages = {147-153},
zbl = {0256.10003},
mrnumber = {0314805},
language = {en},
url = {http://dml.mathdoc.fr/item/2712}
}
Shader, Leslie E. Closed form expressions for several Ramanujan sums. Portugaliae mathematica, Tome 32 (1973) pp. 147-153. http://gdmltest.u-ga.fr/item/2712/