@article{JRAM_1979__309_152136,
     author = {P.D.T.A. Elliott},
     title = {Sums and differences of additive arithmetic functions in mean square.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {21--54},
     publisher = {mathdoc},
     volume = {309},
     year = {1979},
     zbl = {0407.10037},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1979__309_152136/}
}