There is a strong movement by many universities, libraries and organizations to participate in the open access movement in order to provide fast, up-to-date, easily accessible, permanent and free-of-charge sources of information for users of scholarly research. Although many publishers and journals may allow authors to archive their work under certain conditions (there may be copyright restrictions in making an e-print freely available); other publishers are more restrictive. Open access repositories may make research available even prior to a peer-reviewed printed publication, as well as unpublished material. Here lies the challenge to discern between refereed (post-print) and non-refereed (or preprint) material