1. Baumgartner, R., Flesca, S., Gottlob, G.: Visual web information extraction with Lixto. The Very Large Data Bases Journal, 119–128 (2001)
2. Berlea, A., Seidl, H.: Binary queries. In: Proceedings of Extreme Markup Languages, Montreal (2002)
3. Brüggemann-Klein, A., Murata, M., Wood, D.: Regular tree and regular hedge languages over unranked alphabets. Technical report (2001)
4. Comon, H., Dauchet, M., Gilleron, R., Jacquemard, F., Lugiez, D., Tison, S., Tommasi, M.: Tree automata techniques and applications. Online book, 450 pages. Available at (1997), http://www.grappa.univ-lille3.fr/tata
5. Courcelle, B.: On recognizable sets and tree automata. In: Ait-Kaci, H., Nivat, M. (eds.) Resolution of Equations in Algebraic Structures, Algebraic Techniques, vol. 1, ch. 3, pp. 93–126. Academic Press, London (1989)