You've really never seen a Dover book?

http://en.wikipedia.org/wiki/Dover_Books

Publishing works that are in the public domain is their bread and butter.

Kudos for compensation to the downvotes I received. I don't know what happened to the "ask and learn" culture.

I am not a native English speaker, and the term public domain was not self-explanatory (rather, it explained itself in the wrong way).

In Hungarian, public domain means közkincs, which is roughly equivalent to "treasure of the public". So the question seemed reasonable to ask.

I am not a lawyer or expert either but I do not believe it is illegal to sell something in the public domain. That's sort of the point of Public Domain. No one can tell you not to sell it.

You can sell works in the public domain. Go to your book store, I'm sure you can buy a copy of Frankenstein, which is in the public domain. The whole purpose of public domain is that no one owns the copyright, so there are no restrictions to anyone on what may be done with them. I could publish Frankenstein and sell it to people, but I can't stop other people from selling it.

If these documents really are under public domain, then JSTOR can't stop people from distributing the copies obtained from them. However, it is possible for JSTOR to claim copyright on the form of the distributed copies, but not the content (assuming the papers are in the public domain). That is, if they had a JSTOR logo on the papers, or something 'unique', JSTOR may have a basis for claiming copyright infringement. This is assuming they were actually obtained legally, and JSTOR didn't have a strange TOS.

Don't downvote this question, it is valid.

We sell water don't we?

I'm not sure if you're joking. I'm going to, for my own sanity, pretend that you are joking.