C. M. Mugnier-m.-l, Conceptual Graphs : Fundamental Notions. Revue d, Intelligence Artificielle, vol.6, issue.4, pp.365-406, 1992.

G. C. Hurtado-c and . O. Mendelzon-a, Foundations of semantic web databases, PODS '04 : Proceedings of the twenty-third ACM SIGMOD- SIGACT-SIGART symposium on Principles of database systems, pp.95-106, 2004.

M. Chein-m, Polynomial algorithms for projection and matching, Proceedings of the 7th Annual Workshop on Conceptual Structures : Theory and Implementation, pp.239-251, 1993.

P. and H. E. Seaborne-a, SPARQL Query Language for RDF, p.3, 2007.