Svetlozar Nestorov Jeffrey D. Ullman Janet L. Wiener Sudarshan S. Chawathe Representative Objects: Concise Representations of Semistructured, Hierarchial Data. 79-90 ICDE97/P079.pdf 1997 ICDE db/conf/icde/icde97.html#NestorovUWC97 conf/icde/97 http://doi.ieeecomputersociety.org/10.1109/ICDE.1997.581741 journals/jodl/AbiteboulQMWW97 ... books/aw/HopcroftU79 conf/icde/PapakonstantinouGW95 conf/sigmod/QuassWGHLMNRRAUW96 books/cs/Ullman89