@article{JRAM_1978__302_152033,
     author = {D. Suryanarayana and M.V. Subbarao},
     title = {Sums of the divisor and unitary divisor functions.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {1--15},
     publisher = {mathdoc},
     volume = {302},
     year = {1978},
     zbl = {0376.10031},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1978__302_152033/}
}