Francesco Buccafurri Filippo Furfaro Gianluca Lax Domenico Saccà Binary-Tree Histograms with Tree Indices. 861-870 2002 conf/dexa/2002 DEXA http://dx.doi.org/10.1007/3-540-46146-9_85 db/conf/dexa/dexa2002.html#BuccafurriFLS02