Stelios Paparizos Shurug Al-Khalifa H. V. Jagadish Laks V. S. Lakshmanan Andrew Nierman Divesh Srivastava Yuqing Wu Grouping in XML. 128-147 2002 conf/edbtw/2002 EDBT Workshops http://dx.doi.org/10.1007/3-540-36128-6_8 db/conf/edbtw/edbtw2002.html#PaparizosAJLNSW02