The issue of copyright infringement of referenced (non-ELU) works has been discussed previously, with citations and fair use provisions considered. However, the ELUmeta questions I looked at didn't address the issue of reproducing lengthy license terms when excerpts are quoted under those licenses.
It may be that fair use provisions cover these situations, but if not, and if the licenses need to be reproduced, their bulk would dominate that of the answers. Would a link to the license text suffice?
I recently answered an ELU question using a quote from a paper published under the "Open Gaming License version 1.0a" (license terms displayed at the bottom of the linked page), which requires the full text of the copyright notice to be displayed in some situations (clauses 6 and 10, at least).
The quoted portion doesn't look like what the license defines as "Open Game Content", but I'm not a lawyer and I'd like to know whether I should note the "Open Gaming License" in the answer, e.g. (the portion from the dash onwards):
"(text quoted from the source document)" - quoted under the Open Gaming License at the end of the linked paper.