@article{10_37236_202,
     author = {Daniel W. Cranston and Gexin Yu},
     title = {A new lower bound on the density of vertex identifying codes for the infinite hexagonal grid},
     journal = {The electronic journal of combinatorics},
     year = {2009},
     volume = {16},
     number = {1},
     doi = {10.37236/202},
     zbl = {1186.05070},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/202/}
}