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Dental Hygiene Capstone

About These Sources

Good quality research uses all three types of sources. 

Primary sources provide the raw data for your research.

You will use tertiary sources such as encyclopedias, dictionaries and other reference tools to gather background information on your topic and to identify the people, places, dates, organizations, and themes central to your topic.

Secondary sources such as books, scholarly journals, and newspaper article synthesize correct research and help you put your subject in context. Secondary sources are tremendously important for helping to position your argument within the existing research and peer conversation.

TIP: What is considered primary, secondary, or tertiary information may vary according to your field of study. When in doubt, ask your professor.

Differences between Primary, Secondary, and Tertiary sources


Primary sources have the following characteristics:

  • contain direct evidence, first-hand testimony, or eyewitness account of a topic or event
  • provide raw data
  • are commonly diaries, correspondence, photographs


Secondary sources have the following characteristics:

  • use primary data to solve a research problem
  • interpret primary sources
  • are commonly scholarly books and journal articles


Tertiary sources have the following characteristics:

  • books or articles that synthesize and report on secondary sources for general readers
  • are commonly textbooks, encyclopedia articles, or handbooks

Primary and Secondary Sources

In history and the humanities sources are also described as primary or secondary sources. Basically, primary sources are written at the time of the event and secondary sources are written using the primary sources.

onePrimary Sources twoSecondary Sources
  • A newspaper or newspaper article
  • Letters
  • Photographs
  • Diaries
  • Government documents
  • Experimental data
  • Census or survey data
  • Interviews
  • Articles analyzing a theme or motif in a book, film or movie
  • Books or documentaries about a period of time or event in history
  • Biographies
  • Articles published about results or an experimental process

There are some print texts that can be primary or secondary depending why you are using them, or are simply not clearly defined.

  • Memoirs and autobiographies - these are written by the person in question, but typically not while the events they write about are happening
  • Opinion pieces and editorials in newspapers - they may be written close to the time of the event, but include opinion and interpretation of the events
  • Fiction and textbooks - If you are studying how writers within a certain time period wrote, you may concered works of fiction primary sources, but if the book is about a topic or time period it may not even be the best secondary source to use.

Tertiary Sources

Tertiary Sources

  • Dictionaries 
  • Encyclopedias
  • Textbooks
  • Bibliographies
  • Manuals, Guidebooks, Directories, Almanacs
  • Handbooks and Data Compilations