@article{10_37236_1588,
     author = {Daniel Kobler and Andr\'e K\"undgen},
     title = {Gaps in the chromatic spectrum of face-constrained plane graphs},
     journal = {The electronic journal of combinatorics},
     year = {2001},
     volume = {8},
     number = {1},
     doi = {10.37236/1588},
     zbl = {0984.05036},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1588/}
}