Trying to work out where various ancestors were living in "Poland" over past centuries, I think that it would be helpful to have transparent political maps, valid as a particular date, which you could superimpose on unchanging geographical maps, maybe in a loose-leaf format. Does this already exist?
"The Pinguin Historical Atlas of Russia" by John Channon ISBN 0-14-0-51326-4 has many historical maps of the region.
Regards, Moshe Moshe Shavit - Israel mms@actcom.co.il Searching: KATZ, WAGER >from Davidgrodek, now Belarus