Content in the USC Digital Library differs from the Libraries' electronic resources, which provide access to digital content acquired from commercial vendors through purchase, license or subscription. These resources are restricted to USC IP addresses and are not licensable or resalable by USC. In most instances these materials are maintained and archived by the vendor/producer. The Libraries' electronic resources also include selected free (no cost) materials to which a direct link has been provided in the USC Libraries' Catalog and on the Electronic Resources page (open access materials and web pages).