Open Access Overview by Peter Suber; Earlham College. Open Access (OA) literature is digital, online, free of charge, and free of most copyright and licensing restrictions. Many academic web sites, especially as related to electronic journals are supportive of OA concepts.
A subject directory is a service that offers a collection of links to Internet resources submitted by site creators or evaluators and organized into subject categories. Directory services use selection criteria for choosing links to include, though selectivity varies among services.