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They're basically a clone of TBC Wowhead. It's not perfect but it's the closest I know of to a true TBC database. It does have some custom stuff from their core but it's probably the best around.
There is
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but that's a Wrath DB, if you want to go somewhat official, but honestly, their old database is really not very good. If I recall correctly, Wowhead did have old.wowhead.com which was a TBC database but it's gone now and replaced by the Wrath DB (But it was buggy as hell).