Graham Cormode Flip Korn S. Muthukrishnan Divesh Srivastava Effective Computation of Biased Quantiles over Data Streams. 2005 conf/icde/2005 ICDE 20-31 http://csdl.computer.org/comp/proceedings/icde/2005/2285/00/22850020abs.htm db/conf/icde/icde2005.html#CormodeKMS05