At the moment we have a couple of tags dealing with literature in different ways. The most common ones are book-recommendation and literature, where the first one deals specifically with recommendations for books while the other one is broader (but seldomly used). However, we also have scientific-literature and literature-search.
To me, these latter two should be synonyms to literature, since the first one is implied at the site (we are dealing with scientific literature) and most literature questions is dealing with literature searches either way (asking for articles, how to search for sets of articles, what books to look at etc). However, I cannot suggest these synonyms (and almost nobody would be able to vote for them), so I suggest that one of the moderators should merge the tags. Having book-recommendation and literature as the main tags should be sufficient for the site at the moment.