If someone takes content from a question or answer with intent for use in a published work, are they required to attribute the original contributor?
If you look back to when you joined there were details then (which of course many of us don't read). Or just look at the bottom of each page; where it says:
user contributions licensed under cc by-sa 3.0 with attribution required
and there's the answer of the licence and requirements for (re)use.