Where you are in the research process, and the type of information sources you need determines what search tools to use.
Use multi-disciplinary such as the library search engine or Google Scholar. These search engines are broad in scope and enable you to cast a wide search net which helps you see how much information is available on your topic and how the topic is framed conceptually.
Looking for primary sources?
Use specialized databases such as newspaper databases, statistical databases, image databases, news transcripts databases.
All available from the library's A-Z list of databases.
Only a very small portion of primary sources is available through library databases/search engines - these tend to be the 'published' primary sources such as newspapers. When searching for 'unpublished' primary sources, you will need to search the web and consider:
Credit: Jessup Library, Piedmont Virginia Community College