Mark the quote as
<quote src="external" for="name" group="something">text</quote>. The src links out to external pages, the for is the same name used in refs, and the group is the same as in the references.
First check the memcached for previous info and mark the quote accordingly. If the data does not exist fire a job that will then download the external page. When the job is finished, update memcached and purge the old page if it would differ. That would give the next visitor a correct page.
If for is given, then try to find a page through the refs.
The content of the quote tag is used as a pattern, and as such is given a special treatment. Two other tags are promise and explanan. Both are shown as-is, but if the ref is highlighted, then the marked text is highlighted too.
Text marked as promise and explanan have special roles, and can guide further subdivision of arguments and explanandums.