Operational research '72 : proceedings of the 6th IFORS International Conference on Operational Research, Dublin, Ireland, August 21-25, 1972= Actes de la sixieme IFORS Conference internationale de recherche operationnelle, Dublin, Irlande, 21-25 ao ut, 1972 - Ross, Miceal (North-Holland Pub. Co. ; American Elsevier Pub. Co., 1973)