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Understanding Sources: Primary & Secondary Sources

Primary Sources

Primary sources are original source materials created during the period being studied, original empirical research, or raw data. A researcher offers their own interpretation of primary sources to substantiate their claim.

Some examples of primary sources are:

  • Original empirical research (scientific experiments)
  • Government Documents (The Constitution, The National Security Strategy)
  • Raw data (statistics, survey results)
  • Correspondence (letters, emails, tweets)
  • Photographs
  • Maps
  • Speeches
  • Laws and Statutes
  • Artifacts (man-made objects such as pottery or tools)
  • Realia (everyday objects)
  • Official Records (meeting minutes, birth certificate)
  • Diaries
  • Original works of art and literature
  • Oral histories
  • Historical Newspapers
A primary source can be raw empirical data, but the significance of a source may also be for what it reveals, not necessarily because it is factually correct. Primary sources provide insight into a time, a place, a worldview, a groups' perspective, etc.. They are often associated with historical research (i.e., what can we glean about World War I through the letters soldiers sent home from the front). However, it could also be a YouTube video of a religious group. How the researcher engages with a source ultimately determines if it is primary or secondary. A news article may be treated as a primary source (e.g., analyzing media treatment of a topic) or secondary (e.g., citing a news article on the topic as a substantiating source).
Primary sources provide evidence and also allow us to apply meaning. They must be understood in the context of broader social, political, economic, and cultural realities. For example, a paper on the use of unmanned aerial vehicles (UAV) could draw on a variety of primary source material: raw data (government expenditure numbers, casualty statistics, industry revenue), government documents (legislation, hearing transcripts), interviews of citizens affected by drone strikes, and/or opinion surveys. It is up to the researcher to put all the sources together and make a claim about what it all means for the problem or question they set out to answer.

Secondary sources

Secondary sources represent the ideas and scholarship of others. They interpret, analyze, describe, or evaluate  primary and/or other secondary sources.

Some examples of secondary sources are:

  • Non-fiction Books
  • Articles (most of the time, original scientific research can also be primary)
  • Histories
  • Criticism
  • Biographies 
Researchers certainly incorporate secondary sources into their scholarship. We build on the ideas of others and the interpretation of a primary source is often contested. How we apply meaning to a primary source is rarely static, it shifts and evolves over time. And, multiple conflicting interpretations can exist simultaneously (and almost always do). It is up to the researcher to develop a credibly sourced, logical, and evidence based argument for why their interpretation is valid.

Tertiary sources

Tertiary sources are a distillation of secondary and primary source material. These are sources generally used to locate facts or basic information.

Examples of tertiary sources are:

  • Dictionaries
  • Encyclopedias
  • Textbooks
  • Handbooks
  • Almanacs
  • Subject specific reference books
  • and yes...Wikipedia (not citable, but it can help get you started)
In your academic research, sources like Wikipedia or a generalized encyclopedia are not sources you would cite. Utilize these sources to get a basic understanding, break a big topic down, and pick up on significant people, events, terms, and concepts. The types of tertiary sources you would cite are subject or discipline specific, e.g. The Defense & Foreign Affairs Handbook or the PDR Guide to Biological and Chemical Warfare. These are not generalized but provide focused factual data, such as the total manpower of the Chinese army or the clinical effects of exposure to mustard gas.