1B. Mohar,Some applications of Laplace eigenvalues of graphs [ J ]. N ATO ASI Series C, Vol. 497, Kluwr, 1997.
2D. Cvetkovic, M. Doob, H. Sachs, Spectra of graphs. Theory and applications [ M ]. 3rd revised and enlargededition, J. A. Bart verglas, Heidelberg, Leipzig, 1995.
3F. Goldberg, Bounding the gap between extremal Laplacian eigenvalues of graphs [ J ]. Linear AlgebraAppl. 2006.
