1. Bodlaender, H.L.: Treewidth: Characterizations, applications, and computations. Technical report, Utrecht University (2006)
2. Freuder, E.: Complexity of k-tree structured constraint satisfation problem. In: Proc. of AAAI 1990 (1990)
3. Dechter, R., Pearl, J.: Tree Clustering for constraint networks. Artificial Intelligence, 61–95 (1989)
4. Lecture Notes in Computer Science;H. Chen,2005
5. Gottlob, G., Greco, G., Scarcello, F.: The Complexity of Quantified Constraint Satisfaction Problems under Structural Restrictions. In: IJCAI 2005, Proceedings of the Nineteenth International Joint Conference on Artificial Intelligence, pp. 150–155. Professional Book Center (2005)