1. Bannai, E., Ito, T.: Algebraic Combinatorics I: Association Schemes. The Benjamings/Cummings, Menlo Park (1984)
2. Brauer, R.: A characterization of null systems in projective space. Bull. Amer. Math. Soc. 42, 247–254 (1936)
3. Brouwer, A.E., Cohen, A.M., Neumaier, A.: Distance-Regular Graphs. Springer, Berlin (1989)
4. Chow, W.: On the geometry of algebraic homogeneous spaces. Ann. Math. 50, 32–67 (1949)
5. Deng, S., Li, Q.: On the affine geometry of algebraic homogeneous spaces. Acta Math. Sinica. 15, 651–663 (1965)