Sources of information are often considered primary, secondary, or tertiary depending on their originality and proximity of when it was created. Consider if it is an original work, or whether it evaluates or comments on the works of others. Also consider the proximity, or how close the information is to a first-hand account or if it is after the fact.
It can be difficult to distinguish between the three types of sources. They even differ between subjects and disciplines, particularly between the sciences and humanities. By understanding the unique characteristics and features of each, you will be able to identify them and maximize their potential use, and ultimately help you become a more effective researcher and communicate your work to others.
PRIMARY SOURCES DEFINED
Primary sources are first-hand accounts or individual representations and creative works. They are created by those who have directly witnessed what they are describing, and bring us as close to the original event or thought as possible without being filtered, influenced or analyzed through interpretation. They tend to be original documents that don't usually describe or analyze work by others. Primary sources may be published or unpublished works.
Use primary sources when you want to make claims or criticisms, as evidence for theories, or to gain timely perspectives on a topic.
General examples: Letters, diaries, speeches, interviews, correspondence
History: Transcript of speech given by Queen Elizabeth I; newsreel footage of World War II
Literature: Fiction such as Miguel de Cervantes' novel, Don Quixote; Franz Kafka's short story, The Metamorphosis, or poetry by Robert Frost.
Art: Works by artists such as Pablo Picasso's painting, Three Musicians; or Michelangelo's sculpture, David
Social Sciences: Interview transcripts of mentally ill patients; raw, analyzed population data; newspaper articles about events.
Natural Sciences: Analyzed results from biological study; analyzed field data collected by environmental org; original experiments or research.
Examples: court cases, newspaper articles about current events.
SECONDARY SOURCES DEFINED
Secondary sources build off of primary sources with more extensive and in-depth analyses. They summarize, evaluate, and analytically interpret primary material, often by offering a personal perspective. While these are useful to check what other experts in the field have to say, they are not evidence. It is one step removed from the original or primary source. Because secondary sources are published works, they will list their sources of information which can be used to located additional information for your research.
Use secondary sources to see what others have discussed. They can be a good place to gather background information on a topic. You can also use secondary sources to explore what subtopics have already been explored on a given topic.
General examples: Textbooks, monographs (books), encyclopedias, analysis, review articles, dissertations, thesis,
History: Article analyzing Queen Elizabeth I's speech; book recounting battle history of World War II; biographies
Literature: Literary critiques such as an article that examines Cervantes' writing style; paper discussing motifs in The Metamorphosis
Art: Lecture given about Michelangelo's techniques; Criticism or review of Picasso's painting
Social Sciences: News commentaries; Article analyzing results of mental illness study; book that discusses population trends over time; evaluations of social and government policy, law and legislation.
Natural Sciences: Review articles that evaluates the theories and works of others; article on the environmental impact of pollution
TERTIARY SOURCES DEFINED
Tertiary Sources are distillations and collections of primary and secondary sources. The information is compiled and digested into factual representation, so that it does not obviously reflect points of view, critiques or persuasions. Tertiary sources are typically the last to be published in the information cycle. Because it has been filtered through many reviewers, it tends to consist of highly reliable and accurate information, plus contain broad perspectives of topics.
Use tertiary sources for a general overview of your topic and for background information for your research.
General examples: Encyclopedias, directories, dictionaries, handbooks, guides, classification, chronology, and other fact books.
You might find that resources provided by your library can be really helpful, and you can access many of these resources online through your library's website.
Don't forget that our librarians are excellent resources!