Hathitrust's collection, while great, is super intimidating (and annoying) to search through, and while the Duke article is also great, the selection's a little limited. I've gone through and picked out some more books and short story collections and compiled them here: https://babel.hathitrust.org/cgi/mb?a=listis&c=258747804 I'll probably continue adding things to it for a while. I can't vouch for the quality of the works at all, though. I hope it's useful!
Nice job. Here's a link to an archive.org audio search for the year 1923. Be cautious with this because it's all self-tagged stuff, someone might have just been guessing; https://archive.org/details/audio?&and[]=year%3A%221923%22
Also be cautious if someone published in or from Europe instead of America - I discovered the woodcuts on the 1923 thing I was looking at were produced in Belgium originally by an artist that didn't die until the 1970s. According to the Berne Convention I wouldn't be able to use the woodcuts until the 2040s!
