Considering that the site is about Language Learning, studies is inferred.
Should we use the tag at all?
studies, to me, means "studies, published in a peer reviewed journal". Not "I'm doing my language studies before bed."
Perhaps a less ambiguous tag can be used for this. I like @Gille's suggestion of reference-request. It doesn't have the ambiguity shortcomings of research (is the question asking about results of past research, or how to conduct research, etc)?