Look at the library guide defining Primary, Secondary and Tertiary Sources. 
Help Guides from other universities can also help -
              What are primary sources?  from Yale University

A primary source is a document or physical object which was written or created during the period being studied. These sources were present during an experience or time period and offer an inside view of a particular event.  Also included are works created later by an eyewitness or a participant in an event, e.g. memoirs/autobiographies.

Use primary sources to gain timely perspectives on a topic or as evidence for theories.

Examples

Original documents (including excerpts and translations): diaries, speeches, manuscripts, letters, interviews, news film footage, autobiographies, official records, ancient literature, magazine and newspaper articles.

   Literature: Fiction such as Julie March's graphic novel, Blue is the Warmest Color, The Awakening; Kate Chopin's short
   story, or poetry by Sylvia Plath.
   Creative Works: By artists such as Michaelangelo's sculpture, The Venus de Milo or Leonardo da Vinci's painting,
   Mona Lisa.
   History: Newsreel footage of World War II
   Social Sciences: Statistics and raw data
   Natural Sciences: Peer-reviewed experiments or research
 
Reproductions, facsimiles or replicas of original documents, creative works or artefacts are also acceptable
as primary sources.