1. L. Babai. Automorphism group and category of cospectral graphs. Acta Math. Acad. Sci. Hung., 31: 295-306, 1978.
2. L. Babai. Automorphism groups, isomorphism, reconstruction. In R.L. Graham, M. Grötschel, and L. Lovász, editors, Handbook of Combinatorics - Vol. 2, pages 1447-1540. North-Holland, Amsterdam, 1995.
3. L. Babai. Private communication, 2010.
4. M. Behzad, G. Chartrand, and L. Lesniak-Foster. Graphs & Digraphs. Prindle, Weber & Schmidt, Boston, 1979.
5. J. von Below. A characteristic equation associated with an eigenvalue problem on C2-networks. Lin. Algebra Appl., 71: 309-325, 1985.