1. Graphs and Digraphs;Chartrand,1986
2. Steiner distance in graphs;Chartrand;Casopis Pest. Mat.,1989
3. Computers and Intractability: A Guide to the Theory of NP-Completeness;Garey,1979
4. Concrete Mathematics: A Foundation for Computer Science;Graham,1989
5. Graph Theory;Harary,1969