@article{JRAM_1994__454_153645,
     author = {J\"org Br\"udern and Etienne Fouvry},
     title = {Lagrange's {Four} {Squares} {Theorem} with almost prime variables.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {59--96},
     publisher = {mathdoc},
     volume = {454},
     year = {1994},
     zbl = {0809.11060},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1994__454_153645/}
}