Posted By:
Aaron MichielYes, Bushing's guide is highly-recommedned. The prices are a bit inflated, but otherwise it does a great job of ducumenting league president and style changes and variations for both OAL and ONL baseballs and boxes (and a few assorted oddballs thrown in).
Word of warning though, the guide is intended only for "unused" baseballs, not for game-used ones (I don't think there's a mention in the guide at all).
I personally collect "unused" baseballs (and only that to the extent that I wanted a few samples to add to my display). The mintier and more pristine, the better. Other than my Giles and Heydler, I also have a Ban Johnson c. 1925 OAL Reach baseball that I won in last April's Mastro Auction.
I'm not a collector of game-used or trophy baseballs, but I appreciate the topic being raised, nonetheless.