1. Circuits and trees in oriented linear graphs;van Aardenne-Ehrenfest;Simon Stevin,1951
2. The Probabilistic Method;Alon,2008
3. Hypergraphs;Berge,1989
4. Algebraic Graph Theory;Biggs,1993
5. On colouring the nodes of a network;Brooks;Proc. Camb. Philos. Soc.,1941