@article{10_37236_269,
     author = {Michael S. Payne},
     title = {Unit distance graphs with ambiguous chromatic number},
     journal = {The electronic journal of combinatorics},
     year = {2009},
     volume = {16},
     number = {1},
     doi = {10.37236/269},
     zbl = {1185.05063},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/269/}
}