He has a new book, "TREES & HIERARCHIES IN SQL", coming out on this topic. http://books.elsevier.com/us/mk/us/subindex.asp?isbn=1558609202&country=United+States&community=mk&mscssid=U6V4WPGLBHP98MVFTUDPDLFTJVVFDR5B

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>Hey if Mr. Celko happens to reference any online references to this topic in his talk can you post them here? We are doing a couple of tree structures in SQL and VFP and it'd always be good to see his perspective.
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