While reading the general policy on resource recommendation, I was not able to answer if paper/book identification qualifies as an on-topic question.
This is inspired by this Meta question that asks about a particular physics book based on its visual description, content, and particular citation.
Would that type of questions be on-topic? Should it be tagged as resource-recommendations and specific-reference?
I can give you a partial answer: if they are on topic, these questions should be tagged as specific-reference. The difference is that resource-recommendations questions ask for a general class of resources related to a certain topic, where the set of resources that constitute valid answers is large and probably grows over time; on the other hand, specific-reference questions have one particular resource which is the correct answer and will always be the only correct answer. Identification questions like the one you linked are looking for a single specific resource and therefore fall into the latter category.
Now, as for whether these questions are on topic... personally, my instinct is to say no, but to be honest if we only see them very rarely, it's probably not a problem to have a few of these questions around. I guess what I'm concerned about is that these questions are straying into the subject area of books, i.e. they're questions about books rather than questions about physics. I don't want this site to be about books. But any class of questions that we get only a few rare examples of probably isn't doing any harm one way or another.
