Many primary sources are digitally available in specially curated databases. To locate these databases start with the Libraries' Database Finder. Most of these databases will be listed under the “Browse Database by Type” categories of Archives and Manuscripts, Newspapers and Periodicals Current (1990-), Newspapers and Periodicals Historical (pre 1990), and Primary Sources.
The Research Using Primary Source guide was developed by the University of Maryland Libraries' Special Collections. It will clarify how to locate, access, and use primary sources, particularly at the University of Maryland and it's Special Collections