00348nam a2200121Ia 4500082002400000100001700024245006900041260003600110300002100146490004900167500000500216700000500221  a519.501843bB989.CM  aButz, Lothar  aConnectivity in multi-factor designs; a combinatorial approachb  aBerlinbHeldermann Verlagc1982  avii, 190p. Index  aResearch and education in Mathematicsv v. 3  a  a