Find a library that has an archive related to your topic. You can locate resources using ArchiveGrid. You should search this resource by keyword and it will tell you about documents in libraries and archives that relate to your topic. Be sure to note that ArchiveGrid can make you aware of primary sources held in libraries but they will not always be digitized. Often you would be expected to travel to that library to view the sources. Occasionally a copy can be obtained through Interlibrary Loan.
Search Google for gateways to primary sources. The list of collections on the Digital Collections of Primary Sources section of this page is far from exhaustive. There are many, many online collections of primary sources. Enter your topic into a Google search and add one of the following phrases to your search in order to identify an appropriate collection: primary sources, archive, documents, historical resources, images, photographs.
Use secondary and tertiary sources to locate primary sources. Though you are focusing your search on primary sources, scholarly secondary sources (books, articles etc.) and tertiary sources (encyclopedia entries, bibliographies etc.) often contain mention of archives or other resources that contain primary sources.
Be creative and think critically. Not every subject will have the same number or same kind of primary sources available. Some may be very easy to find while others present a great challenge. When looking for primary sources think about what kinds of documents or records might exist. Where or when might they have been produced? What organization or person might have preserved them?
There may be primary sources contained within books or other resources already housed in Nimitz Library. In order to find out what's available in Nimitz, search the library's catalog by clicking on the Books search tab on the library's homepage.
Once there, enter a keyword or two about your topic along with one of the following phrases which could indicate a primary source: