 Classification-based approaches work well for small numbers of candidate authors, but only similarity-based methods  are applicable for larger numbers of authors or for authors beyond the training set .
<coherence>  Classification-based approaches work well for small numbers of candidate authors, but only similarity-based methods  are applicable for larger numbers of authors or for authors beyond the training set .
 Classification-based approaches work well for small numbers of candidate authors, but only similarity-based methods , which are applicable for larger numbers of authors or for authors beyond the training set .