D. Aumueller, H. Do, S. Massmann, and E. Rahm. Proceedings of the 2005 ACM SIGMOD International Conference on Management of Data, page 906--908. New York, NY, USA, ACM, (2005)
D. White. (2014)cite arxiv:1401.2651Comment: 27 pages. Originally written in 2009 and hosted on my website, I've decided to put it on the arXiv as a more permanent home. The paper is primarily expository, so I don't really know where to submit it, but perhaps one day I will find an appropriate journal.