Georg Gottlob, Christoph Koch, Klaus U. Schulz. Conjunctive Queries over Trees. In Alin Deutsch, editor, Proceedings of the Twenty-third ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, June 14-16, 2004, Paris, France. pages 189-200, ACM, 2004. [doi]
Abstract is missing.