It's a process: Start with background research for a basic understanding of the key facts and then conduct secondary source research and reading. This usually yields better luck finding references to relevant primary sources.
Techniques for locating relevant primary sources in secondary sources:
Keep a list of keywords (important names, places, dates, organizations, corporations, etc.) while you are reading secondary sources. Search these in online repositories of primary sources, such as the ones listed on this very page.
Scan the bibliographies of your books and articles to see what primary sources they may have cited.
The bibliographies of dissertations and theses are often a fantastic resource for locating primary and secondary sources, too.
Dissertations/Theses (SHU eRepository)eRepository is a service offered by the Seton Hall University Libraries and Seton Hall Law to service the needs of the SHU community in the preservation and dissemination of scholarly works.