@article{JRAM_1978__302_152036,
     author = {R. Sivaramakrishnan},
     title = {Multiplicative even functions (mod r). {II} {Identities} involving {Ramanujan} sums.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {44--50},
     year = {1978},
     volume = {302},
     zbl = {0376.10007},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1978__302_152036/}
}