Fourth is mainly about some search resources, like Derwent patent information, patent database of MIT, American AIDS patents project, IBM patent server and other patent database and search engines.

• 如德温特专利信息、麻省理工学院的专利数据库、美国艾滋病专利项目、IBM专利服务和其他的专利数据库和搜索引擎。网站同时提供了有关声频专利的相关网站。