This is truly the backbone of US Currency collecting and we are constantly trying to maintain a varied inventory in respect to both variety and condition. All entries refer to the Friedberg book "Paper Money of the United States."
This reference (just released Oct. 2011), designed for the specialist and dealer, offers the most complete data to be found anywhere for small-size currency, organized and listed by specific series, including accurate population figures for each. The book also contains detailed tutorial information. Most up-to-date census for all U.S. small-size currency.