2012/1/21 John R. Frank <jrf@mit.edu>

verify that they ref'ed the central node before that date?  What about pages that did ref and no longer do?  (probly rare?)

I think this information is not kept explicitely, so the option is brute force to gather them if you really need. Alternative idea is to get a dump that is closest to the given date, and use that (but I am not sure that all the dumps are publicly available backwards).