M.O. Albertson and K.L. Collins, Symmetry breaking in graphs, Electron. J. Combin. 3 (1996), #R18.
 K.L. Collins and A.N. Trenk, The distinguishing chromatic number, Electron. J. Combin. 13 (1) (2006),
 D.W. Cranston, Proper distinguishing colorings with few colors for graphs with girth at least 5. arXiv
 J. Gross and J. Yellen, Handbook of Graph Theory, CRC Press, Boca Raton, 2004.
 C. Laflamme and K. Seyffarth, Distinguishing chromatic numbers of bipartite graphs, Electron. J. Combin.
16 (1) (2009), #R76.