1. Schaum's outline of graph theory;Balakrishnan,1989
2. Bell South, INDETEC International, Sprint and US West (1997), Benchmark Cost Proxy Model, Release 3.0, Model Methodology, December 11.
3. Discrete mathematics;Biggs,1994
4. Bush, C. A., Kennet, D. M., Prisbrey, J., Sharkey, W. W., & Gupta, V. (1999). Computer Modeling of a local Telephone Network, October.
5. Introductory graph theory;Chartrand,1985