Daniela Barbosa, who is the business development manager for Synaptica at Dow Jones Client Solutions has written a fabulous eBook explaining how to mix taxonomies built by professionals and folksonomies, which let users tag content as they see fit
M. Haridas, and D. Caragea. On the Move to Meaningful Internet Systems: OTM 2009, volume 5871 of Lecture Notes in Computer Science, Springer, Berlin / Heidelberg, (2009)
P. Cimiano, S. Staab, and J. Tane. Proceedings of the ECML/PKDD Workshop on Adaptive Text Extraction and Mining, Cavtat-Dubrovnik, Croatia, page 10-17. (2003)