Types of Sources When Researching

There are different kinds of sources of information or evidence that are categorized as primary, secondary, or tertiary materials. These classifications are based on originality, time, and origin. This informs the reader if the author is reporting information first hand or conveying the experiences second hand. Determining if a source is primary, secondary or tertiary can be hard to distinguish. Below are descriptions of the categories of sources with examples to help when researching.

 If you need further assistance, please visit us, call the Reference Desk: (708) 649-7485, or email: mpref@mpplibrary.org.

Primary Sources

Primary sources provide first hand accounts of an event or time period. Primary sources display original thinking, report on new discoveries or events, or share new information.

Examples of Primary Sources:


  • Original Research: Results of experiments, interviews, questionnaires, studies, surveys, archaeological digs
  • Personal Works: Diaries, identification papers, journals, letters, memoirs and autobiographies, speeches, theses
  • Government Records: Parliamentary proceedings, bills, acts, treaties, census data, court transcripts
  • Corporate Records: Account books, e-mails, invoices, purchase orders, minutes, annual reports
  • Works of Literature: Novels, plays, poetry, short stories
  • Art and Artifacts: Paintings, sculptures, photographs, coins, objects
  • Journal Articles Reporting Original Research
  • Original Audio and Video Recordings: Feature films, news footage, performances
  • Music: Notated (print), recorded
  • Other: Advertisements, data files, maps, newspaper reports, patents, posters, and public opinion poll

Secondary Sources

Secondary sources provide second hand accounts regarding an event or time period. This can include an argument, interpretation, conclusion, or summary based on information or facts found from primary sources.

Examples of Secondary Sources:

  • Biographies
  • Books (literary criticism and textbooks)
  • Editorials and Commentaries
  • Encyclopedias 
  • Journal Articles (not on original research)
  • Reviews
  • Theses (not on original research)

Tertiary Sources

Tertiary sources help researchers identify and locate primary and secondary sources.

Examples of Tertiary Sources:

  • Bibliographies
  • Indexes
  • Abstracts
  • Encyclopedias 
  • Other Reference Resources

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