1. Eigenvalues and expanders;Alon;Combinatorica,1986
2. Algebraic Graph Theory;Biggs,1974
3. Spectra and colourings of weighted graphs;Bolla,1990
4. Spectra of Graphs;Cvetković,1979
5. Eigenvalues of a graph and its imbeddings;Doob;J. Combin. Theory Ser. B,1974