The Semantic Web: Research and Applications 6th European Semantic Web Conference, ESWC 2009 Heraklion, Crete, Greece, May 31–June 4, 2009 Proceedings - Aroyo, Lora; Traverso, Paolo; Ciravegna, Fabio; Cimiano, Philipp; Heath, Tom; Hyvönen, Eero; Mizoguchi, Riichiro; Oren, Eyal; Sabou, Marta; Simperl, Elena (Springer Berlin Heidelberg, 2009)