Link resolver it's a paying service (e.g. Linksolver offered by Ebsco) and it appears like a simple 'button' to click.
When you find a record in a bibliographic database, the link resolver searches in the e-resources (full text databases, aggregators, e-journals, etc.) of your institution for the full text (usually PDF). If there is no full text avaible, then it will link you to the opac or the document delivery service.
