In an EBSCO or Proquest database, limit your search to scholarly/peer-reviewed journals, and make sure that your article has a "method" section.
It is also possible to limit your search to "Primary Source Documents" in some databases.
See below for what an original research article looks like:
Below are some examples of primary source types that work particularly well with historical topics. Remember that all of these would be *from the time period being studied*: