Online DBLP entries are available for Apostolos Papadopoulos and the following references. (The DiSC DBLP references below have been taken from the Novemember 1998 DBLP.)
Apostolos Papadopoulos,
Yannis
Manolopoulos: Multiple Range Query Optimization in Spatial Databases.
ADBIS
1998: 71-82