I've only seen the Celebrate the Century series once; it was in an e-Bay auction and it was bought before I could bid. The books are meant to track American history through stamp collecting. Apparently, there are 10 books in this series, one for each of the decades of the 1900's (similar to Our American Century and some of the other series) and each volume is 96 pages. All of the volumes together come with a slipcover / case and they were available through the Post Office. I have found 2 ISBN numbers for this series; 0783553188 and 078355317X, but they are only for volumes 1 and 2.