Aren't this the same books that commonly breaks the license requirement of Wikipedia?
In particularly the kindle versions, if they take data from Wikipedia, then the book need to be licensed under CC-ShareAlike license and users could re-distribute copies freely. If not, then the company behind the book is basically doing copyright infringement, in large scale, and for profit.
For copying texts from public domain, I find that the written language evolve faster than copyright expires. For example, the Swedish written language has changed so much in the last 100 years that middle aged adults can not understand 80% of the words written in many books which are still under copyright.
There's nothing in the CC-ShareAlike license about only being able to use the content for non-commercial purposes. I think that as long as you released the Kindle book with the CC-ShareAlike license, you could still charge for it and it would be legal.
In particularly the kindle versions, if they take data from Wikipedia, then the book need to be licensed under CC-ShareAlike license and users could re-distribute copies freely. If not, then the company behind the book is basically doing copyright infringement, in large scale, and for profit.
For copying texts from public domain, I find that the written language evolve faster than copyright expires. For example, the Swedish written language has changed so much in the last 100 years that middle aged adults can not understand 80% of the words written in many books which are still under copyright.