1. Bose R.C.: Symmetric group divisible designs with the dual property. J. Stat. Plan. Inference 1, 87–101 (1977).
2. Brouwer A.E., Haemers W.H.: Spectra of Graphs. Springer, New York (2012).
3. Godsil C.D., McKay B.D.: Feasibility conditions for the existence of walk-regular graphs. Linear Algebra Appl. 30, 51–61 (1980).
4. Haemers W.H., Kharaghani H., Meulenberg M.A.: Divisible design graphs. J. Comb. Theory Ser. A 118, 978–992 (2011).
5. Meulenberg M.A.: Divisible design graphs. Master’s Thesis, Tilburg University (2008).