title: metrics for accessing heterogeneous data : is there any hope ? ( panel ). authors: michael stonebraker , nicholas j. belkin , gio wiederhold , erich j. neuhold , leonard j. seligman. venue: vldb. year: 1995
title: sql open heterogeneous data access. authors: berthold reinwald , hamid pirahesh. venue: international conference on management of data. year: 1998