<p>Any threshold for splitting/merging is somewhat arbitrary, but I personally think the <a href="https://stats.stackexchange.com/questions/tagged/references" class="post-tag" title="show questions tagged &#39;references&#39;" aria-label="show questions tagged &#39;references&#39;" rel="tag" aria-labelledby="tag-references-tooltip-container">references</a> tag already meets our needs sufficiently. Specifics like books/textbooks/papers can be noted in the question title and body.</p>
