Daniel W. Cranston, Gexin Yu. A New Lower Bound on the Density of Vertex Identifying Codes for the Infinite Hexagonal Grid. Electr. J. Comb., 16(1), 2009. [doi]
@article{CranstonY09,
title = {A New Lower Bound on the Density of Vertex Identifying Codes for the Infinite Hexagonal Grid},
author = {Daniel W. Cranston and Gexin Yu},
year = {2009},
url = {http://www.combinatorics.org/Volume_16/Abstracts/v16i1r113.html},
researchr = {https://researchr.org/publication/CranstonY09},
cites = {0},
citedby = {0},
journal = {Electr. J. Comb.},
volume = {16},
number = {1},
}