Ahmed K. Elmagarmid Calton Pu Guest Editors' Introduction to the Special Issue on Heterogeneous Databases. 175-178 1990 22 ACM Comput. Surv. 3 db/journals/csur/csur22.html#ElmagarmidP90 db/journals/csur/ElmagarmidP90.html CSURs1/csur22/P175.pdf journals/csur/BatiniL86 ... journals/tkde/HsiaoK89