1. N. Deo, Z. Nikoloski, F. Suraweera. Generation of Graceful Trees. The 33rd Southeastern International Conference on Combinatorics, Graph Theory and Computing, Boca Raton, FL, Mar. (2002), 4-8.
2. Joseph A. Gallian, A Dynamic Survey of Graph Labelling. he Electronic Journal of Combinatorics, 14 (2013), \#DS6.
3. Harary F. and Palmer E. M. Graphical enumeration. Academic Press, 1973.
4. M. E. J. Newman, A. -L. Barabási, and D. J. Watts, The Structure and Dynamics of Networks. Princeton University Press, Princeton (2006).
5. The structure and function of complex networks;Newman;SIAM Rev.,2003