@article{GDZPPN00221055X,
title = {Lower bounds for sums of Barban-Davenport-Halberstam type.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {435},
year = {1993},
pages = {163-174},
zbl = {0776.11056},
url = {http://dml.mathdoc.fr/item/GDZPPN00221055X}
}
Liu, H.-Q. Lower bounds for sums of Barban-Davenport-Halberstam type.. Journal für die reine und angewandte Mathematik, Tome 435 (1993) pp. 163-174. http://gdmltest.u-ga.fr/item/GDZPPN00221055X/