1. Wang Ke, Liu Huiqing. Schema Discovery for Semistructured Data [EB/OL].[2008-02-10]. http:zSzzSzwww.iscs.nus.edu.sgzSz:_wangkzSzpubzSzkdd1.pdf/wang97schema.pdf.
2. Miyahara T, Shoudai T, Uchida T, et al. Discovery of Frequent Tree Structured Patterns in Semistructured Web Documents [EB/OL].[2008-02-10]. http://www.springerlink.com/content/40b73r9aqpepp1yr/fulltext.pdf .
3. Zaki M J. Efficiently Mining Frequent Trees in a Forest[EB/OL]. [2008-02-10]. http://www.lans.ece.utexas.edu/course/ee380l/03sp/papers/71.pdf .
4. Asai T, Abe K, Kawasoe S, et al. Efficient Substructure Discovery from Large Semi-Structured Data[EB/OL]. [2008-02-10]. http://www.siam.org/meeings/sdm02/proceedings/sdm02-10.pdf .
5. Wang Chen, Hong Mingsheng, Wang Wei, et al. Chopper: Efficient[J]. Algorithm for Tree Mining. 2004,(3): 309–319.