D. Schall, and F. Skopik. Proceedings of the 15th international conference on Advances in databases and information systems, page 285--301. Berlin, Heidelberg, Springer-Verlag, (2011)
L. Antiqueira, and L. Costa. Proceedings of the 2nd Workshop on Complex Networks (CompleNet'2010), volume 116 of Communications in Computer and Information Science, page 46-56. Springer, (2011)