1. Sequencing problems in two-server systems;Calderbank;Maths. of OR,1985
2. Should the two headed disk be greedy? — Yes It should;Hofri;Info. Pro. Letters,1988
3. The number of cylinders travelled for a single query on a two seek arm backing storage device;Deighton;Database Technology J.,1992
4. Database queries on three-headed backing storage devices;Deighton;Database Technology J.,1993