V. C. Barbosa and E. Gafni, Concurrency in heavily loaded neighborhood- constrained systems, ACM Trans. on Programming Languages and Systems 11 (1989) 562-584.
 J. A. Bondy and U. S. R. Murty, Graph Theory with Applications, American Elsevier, 1979.
 Wu-Hsiung Lin and Hong-Gwa Yeh, A note on circular colorings of edge-weighted digraphs, Taiwanese Journal of Mathematics, 15 (2011) 2159-2167.
 D. B. West, Introduction to Graph Theory, 2nd edition, Prentice Hall, 2001.
 Hong-Gwa Yeh and Xuding Zhu, Resource-sharing system scheduling and circular chromatic number, Theoretical Computer Science 332 (2005) 447-460.
 Hong-Gwa Yeh, A dynamic view of circular colorings, preprint, 2006. http://arxiv.org/abs/math/ 0604226
 Hong-Gwa Yeh, Class Notes for Graph Structure Theory, Fall 2016, National Central University, Taiwan.
 Hong-Gwa Yeh, A method to obtain lower bounds for circular chromatic number, Taiwanese Journal of Mathematics, 12 (2008) 997-1005.
 Hong-Gwa Yeh, A connection between circular colorings and periodic schedules, Discrete Ap- plied Mathematics, 157 (2009) 1663-1668.
 Xuding Zhu, Circular chromatic number: a survey, Discrete Math. 229 (2001) 371-410.
 Xuding Zhu, Circular colouring and orientation of graphs, J. Comb. Theory, Ser. B, 86 (2002) 109-113.
 Xuding Zhu, Recent developments in circular colouring of graphs, In M. Klazar, J. Kratochvil,
J. Matousek, R. Thomas, and P. Valtr, editors, Topics in Discrete Mathematics, pages 497-550, Springer, 2006.