1. L. Babai, D. Yu. Grigoryev and D. M. Mount, Isomorphism of graphs with bounded eigenvalue multiplicity, Proc. 14th ACM STOC (1982), 310–324.
2. E. Bannai and T. Ito, Algebraic Combinatorics I, Benjamin/Cummings, Menlo Park, CA, 1984.
3. N. Biggs, Algebraic Graph Theory, 2nd edition, Cambridge University Press, Cambridge, 1993.
4. A. E. Brouwer, A. M. Cohen and A. Neumaier, Distance-Regular Graphs, Springer-Verlag, Berlin, 1989.
5. R. A. Brualdi, Some applications of doubly stochastic matrices, Linear Algebra Appl. 107 (1988), 77–100.