1. Orthogonal arrays of strength two and three;Bose;Ann. Math. Statist.,1952
2. Fractional replication in asymmetrical factorial designs and partially balanced arrays;Chakravarti;Sankhya,1956
3. Hypercubes of strength d leading to confounded designs in factorial experiments;Rao;Bull. Cal. Math. Soc.,1946
4. Saha, G. M. 1975). Some results in tactical configurations and related topics. To appear in Utilitas Nathematica.