Akram Shehadi Saynez María Josefa Somodevilla García Manuel Martín Ortiz Ivo Humberto Pineda Torres H-Tree: A data structure for fast path-retrieval in rooted trees. 25-32 2007 ENC http://dx.doi.org/10.1109/ENC.2007.26 conf/enc/2007 db/conf/enc/enc2007.html#SaynezGOT07