K. Cheung, H. Frost, M. Marshall, E. Prud'hommeaux, M. Samwald, J. Zhao, and A. Paschke. BMC Bioinformatics, (2009)"We have explored a tool called "FeDeRate", which enables a global SPARQL query to be decomposed into subqueries against the remote databases offering either SPARQL or SQL query interfaces.".
S. Chalmers, J. Nilsson, H. Edler, and G. Kemp. Third Asian Semantic Web Conference (ASWC2008) Workshop Proceedings: The Semantic Web - a view on data integration, reasoning, human factors, collective intelligence and technology adoption., page 270-275. Bangkok, Thailand, (December 2009)