This encyclopedia is a great place to get background information on news agencies as well as types of media bias. The focus is mostly on American news media but can help you understand issues of media bias generally.
News websites are a good place to search but may be somewhat limited. Many do not have archives available for free. Others are difficult to search for past events. The news websites listed below should have enough information on the topic.
Use the following databases to search across larger collections of news sources.