Erratum to: J Clust Sci (2012) 23:203–219 DOI 10.1007/s10876-011-0420-4

Because the Electronic Supplementary Material was not supplied at the same time as the original version of their article, the Electronic Supplementary Material was not published with the original version of the article. The Electronic Supplementary Material can be found at doi:10.1007/s10876-013-0640-x