Based upon what I could find, you're correct in that it appears that the 1st and 2nd are public domain, as their copyrights were not renewed. Furthermore, it appears that most of the 1st edition was already public domain, because before the 1970s if a work was published without a copyright notice on it, it lost copyright protection. The first edition was published 3 months prior to copyright registration without a story at the end (the version with the story was published 3 months after and with the notice of copyright). But in any regard, it is public domain.
Now as to whether "some say it is ok, and others say no", that might be a statement of morality. It IS public domain, so you can legally do so. There's a lot of things that you can legally do that's not "okay" to do (such as protest the war at a funeral of a service member). That might be a statement of morality. But as to legality, if the copyright was not renewed, then every word in THAT version is public domain. Even if subsequent versions of the book use the same wording, etc... to the extent that those words are in a version that's public domain, they can be used by anyone.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Thank you, ***** ***** luck to you!