Testing Containment of XPath Expressions in Order to Reduce the Data Transfer to Mobile Clients
S. Böttcher, R. Steinmetz, in: Advances in Databases and Information Systems, 7th East European Conference, ADBIS 2003, Springer, 2003, pp. 400–410.

A DTD Graph Based XPath Query Subsumption Test
S. Böttcher, R. Steinmetz, in: Database and XML Technologies, First International XML Database Symposium, XSym 2003, Berlin, Heidelberg, 2003, pp. 85–99.

A Subset Test for XPath Expressions under DTDs
S. Böttcher, R. Steinmetz, in: 20th British National Conference on Databases, BNCOD 20, Poster Papers, 2003, pp. 43–45.