Primary sources are documents or objects created at the time of the study, for instance, diaries, contemporary newspapers, journals, literary works. Statistics, surveys, and other data are also primary sources. Physical objects such as artifacts produced at the studied time period can also be used as primary source materials.
Tips: Find names of authors who lived in the time period under study, and search for works from these authors in the Library Catalog.
Try to find old imprints, rare books, archival materials if appropriate. Good sources are the Online Archive of California leading to resources in UCLA's Special Collections and the Europeana Library leading to digitized resources all over Europe.