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2. On Coloring the Nodes of a Network;Brooks;Proc. Cambridge Philos. Soc.,1941
3. Some Applications of Probability to Graph Theory and Combinatorial Problems;Erdös,1964
4. Probabilistic Methods in Combinatorics;Erdös,1974
5. J. Folkman and J.F. Lawrence, Oriented Matroids, J. Combinatorial Theory, Ser. B (To appear).