On Testing Satisfiability of Tree Pattern Queries. - Laks V. S. Lakshmanan; Ganesh Ramesh; Wendy Hui Wang; Zheng (Jessica) Zhao (VLDB, 2004)

Answering Tree Pattern Queries Using Views. - Laks V. S. Lakshmanan; Wendy Hui Wang; Zheng (Jessica) Zhao (VLDB, 2006)