1. A note on Fisher's inequality for balanced incomplete block designs;Bose;Ann. Math. Stat.,1949
2. On a combinatorial problem;de Bruijn;Indagationes Math.,1948
3. A Treatise on the Circle and the Sphere;Coolidge,1916
4. Combinatorial Theory;Hall,1967
5. Combinatorial Geometry in the Plane;Hadwiger,1964