A primary source, also called "source material" and sometimes "original sources", refers to
"a document or record containing firsthand information or original data on a topic.... Primary
sources include original manuscripts, articles reporting original research or thought, diaries,
memoirs, letters, journals, photographs, drawings, posters, film footage, sheet music, songs,
interviews, government documents, public records, eyewitness accounts, newspaper clippings, etc."
(Dictionary for Library and Information Science / Joan M. Reitz, 2004).
To find primary sources in OneSearch add terms such as: sources, letters, documents, papers, etc. to your search.