1. Algebraic Graph Theory;Biggs,1993
2. Graph Theory with Applications;Bondy,1976
3. J. Denes, Connections between transformation semigroups and graphs, in: Theory of Graphs, Internat. Sympos., Rome, 1966, Gordon and Breach, New York, Dunod, Paris, 1967, pp. 93–101
4. On Cayley graphs of bands;Fan;Semigroup Forum,2007
5. Fundamentals of Semigroup Theory;Howie,1995