@article{10_4153_CMB_1990_039_5,
     author = {Aharonov, Dov},
     title = {The {Hexagonal} {Packing} {Lemma} and {Discrete} {Potential} {Theory}},
     journal = {Canadian mathematical bulletin},
     pages = {247--252},
     year = {1990},
     volume = {33},
     number = {2},
     doi = {10.4153/CMB-1990-039-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1990-039-5/}
}