1. The main part of spectrum, divisors and swiching of graphs;Cvetković;Publ. Inst. Math. (Beograd),1978
2. Spectra of Graphs;Cvetković,1982
3. Eigenspaces of Graphs;Cvetković,1997
4. Algebraic Combinatorics;Godsil,1993
5. Constructing cospectral graphs;Godsil;Aequat. Math,1982