title: distance-based indexing for high-dimensional metric spaces. authors: z. meral özsoyoglu , tolga bozkaya. venue: sigmod conference. year: 1997
title: the a-tree : an index structure for high-dimensional spaces using relative approximation. authors: yasushi sakurai , masatoshi yoshikawa , shunsuke uemura , haruhiko kojima. venue: very large data bases. year: 2000