I recently unburied my head from the sand and saw an article on
resources for catalogers of early printed maps. The article is from the
Journal of Map & Geography Libraries (JMGL), v.3, no. 2, 2007 and
written by Nancy Kandoian. I'm not sure if this has been discussed on
the list yet - but the title of the article is: "Cartobibliography for
catalogers: reference materials to support the identification of early
printed maps."

There is a great list of reference materials that aren't only useful for
the super early printed maps - but also maps dating into the early 20th
Century.  It's a great resource for catalogers and I highly recommend it
this article. There are a number of other, really interesting looking
articles in that issue of JMGL as well - if you have some extra time -
it's worth reading.

Angie
AGSL UWM