1. Spectrum of the graph of n-tuples;Cvetković;Publikarije Elektrotechnikog Facultata Univerziteta u Beogradu No. 288,1969
2. A geometric interpretation of the least eigenvalue of a line graph;Doob,1970
3. On the polynomial of a graph;Hoffman;Amer. Math. Monthly,1963
4. Some recent results on spectral properties of graphs;Hoffman;Beiträge zur Graphentheorie,1968