1. Graphs and their spectra;Cvetkovic,1971
2. Graph Theory;Harary,1969
3. On the exceptional case in a characterization of the arcs of a complete graph;Hoffman;IBM J. Res. Develop.,1960
4. The number of trees in a graph I, II;Kelmans;Automat. Remote Control,1965
5. The number of trees in a graph I, II;Kelmans;Automat. Remote Control,1966