There is pretty big block of early AT trail guides up on ebay. Mostly 1st and 2nd editions, very pricey but generally very rare. The interesting part of the 1st editions that in many cases the trail was not complete and the route at the time varied substantially from the current one including that the southern end was on MT Oglethorpe I have been looking for awhile for a 1st edition AT guide to Maine. Its rare, supposedly MATC doesn't even have a copy. There is supposedly one in the Maine state library. I bid on one once several years ago that ended up selling for around $800.
I do have a second and third edition of the Maine guides that are prewar (1934 and 1937) and only published three years apart, the difference was the second edition was written before the AT was finished while the third one it was. The AT in Maine was much different at the time, far more like the last section of the 100 mile wilderness past White Cap. The trail weaved around many of the mountains and many of the overnight spots were sporting camps on ponds and rivers. The big relocation onto the NPS corridor along with land claims settlement in Maine moved a lot of the trail up on the ridges.