@article{MOMA_1996__121_3_178731,
     author = {J.M. Wills and S. Vassallo},
     title = {Coverings {Sets} for {Plane} {Lattices.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {381--390},
     publisher = {mathdoc},
     volume = {121},
     number = {3},
     year = {1996},
     zbl = {0853.52020},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1996__121_3_178731/}
}