Jorge Pérez Marcelo Arenas Claudio Gutierrez nSPARQL: A Navigational Language for RDF. 66-81 2008 International Semantic Web Conference http://dx.doi.org/10.1007/978-3-540-88564-1_5 conf/semweb/2008 db/conf/semweb/iswc2008.html#PerezAG08