R. Sampaio, G. Sobral, and Y. Wakabayashi.
" Minimum Density of Identifying Codes of Hexagonal Grids with a Finite Number of Rows", in Proceedings of the 7th Theory of Computation Meeting, NiterĂ³i, 2022, pp. 145-148, doi: https://doi.org/10.5753/etc.2022.223348.