Sathish Govindarajan Tamás Lukovszki Anil Maheshwari Norbert Zeh I/O-Efficient Well-Separated Pair Decomposition and Applications. 585-614 2006 45 Algorithmica 4 http://dx.doi.org/10.1007/s00453-005-1197-3 db/journals/algorithmica/algorithmica45.html#GovindarajanLMZ06