The Tower Treasure (Hardy Boys #1)

Grosset & Dunlap never states printings, so the ad lists and pre-text series list are the working reprint tell: any list carrying titles published after The Secret of the Old Mill is a later printing in the same 1927 format. The text was rewritten in 1959; every post-1959 issue carries the revised text and is a first thus at best. Picture-cover (illustrated board) issues from the 1960s onward, and the Applewood Books facsimile reprints of the original text begun in 1991 (including the Collector's Boxed Set, ISBN 9781557091536), reproduce the original text but are modern reprints, not the 1927 first.