“Questions looking for specific references” is not a useful tag. It characterizes answers, not questions.
I'm perfectly aware that several sites have such a tag, including one that I moderate (where it's called
reference-request). But the tag serves no useful function. It vaguely indicates the nature of the expected answers, but it is not a subject of expertise, and it is not useful in a search (if I'm looking for a reference for X, I won't limit my search to questions with the tag
reference-request, because many answers on questions that weren't specifically requesting references do include references).
So forget about looking for a name for a tag meaning “questions looking for specific references”. For the meaning “references in books”, I like muru's suggestion allusions.