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ENGI 110: Brahma (Spring 2023): Primary Sources in Engineering

Primary Sources in the Sciences

What are primary sources?

  • Primary sources provide first-hand testimony or direct evidence concerning a topic under investigation. They present original thinking, report a discovery, or share new information.

  • They are created by witnesses or recorders who experienced the events or conditions being documented. They are from the time period involved and have not been filtered through subsequent interpretation or evaluation.

Context is important

The types of information that can be considered primary sources may vary depending on the subject discipline, and also on how you are using the material. For example:

  • A magazine article reporting on recent studies linking the reduction of energy consumption to the compact fluorescent light bulb would be a secondary source.
  • A research article or study proving this would be a primary source.
  • However, if you were studying how compact fluorescent light bulbs are presented in the popular media, the magazine article could be considered a primary source.

Tip: If you are unsure if a source you have found is primary, talk to your instructor or librarian.

What are secondary sources?

  • Secondary sources are interpretations and evaluations of primary sources.
  • Secondary sources are not evidence, but rather commentary on and discussion of evidence.
  • Books, articles, etc. which use primary sources as the source would be secondary.

Health Sciences, Sciences, Engineering 

The idea of primary sources in the sciences are a little bit different than primary sources in the humanities or social sciences.  In the sciences, the focus is on the research.  Primary sources are ones written by the scientists who performed the experiments - these articles include original research data.  Secondary sources are ones that summarize or compare lots of research in a particular area.

So how can you tell if a science article is a primary source?  Primary research articles will include sections about:

  • methodology -  explaining how the experiment was conducted
  • results - detailing what happened and providing raw data sets (often as tables or graphs)
  • conclusions - connecting the results with theories and other research
  • references - to previous research or theories that influenced the research

Primary sources in the sciences are original materials or information on which other research is based. Primary sources are also sets of data, such as health statistics, which have been tabulated, but not interpreted.

Examples include: Journal articles of original research (written by person who did the research), patents, conference papers, dissertations, technical reports, Einstein’s diary.

Sources are considered primary, secondary, or tertiary depending on the originality of the information presented and their proximity or how close they are to the source of information.

Many databases feature an advanced or limits section, which sometimes allow you to limit to publication type or research methodology (clinical trial, comparative study, etc).

Primary Sources in the Sciences....

  • Report original research, ideas, or scientific discoveries for the first time
  • Report results/findings/data from experiments or research studies
  • May also be referred to as primary research, primary articles, or research studies
  • DO NOT include meta-analysis, systematic reviews, or literature reviews - these are secondary sources
  • Are frequently found in peer-reviewed or scholarly journals
  • Should explain the research methodology used (randomized controlled trial, etc)
  • Frequently include methods, results, and discussion sections
  • Are factual, not interpretive

More on Types of Sources...

Sources are considered primary, secondary, or tertiary depending on the originality of the information presented and their proximity or how close they are to the source of information. This distinction can differ between subjects and disciplines. In the sciences, research findings may be communicated informally between researchers through email, presented at conferences (primary source), and then, possibly, published as a journal article or technical report (primary source). Once published, the information may be commented on by other researchers (secondary sources), and/or professionally indexed in a database (secondary sources). Later the information may be summarized into an encyclopedic or reference book format (tertiary sources).


Primary Sources

Primary sources are original materials/information on which other research is based. It includes journal articles of original research, conference papers, dissertations, technical reports, and patents. Primary sources are also sets of data, such as health statistics, which have been tabulated, but not interpreted.

  • Journals or Periodicals: main type of publication in which scientific research is reported. May be published by learned societies or by commercial publishers. A researcher(s) submits an article to a journal. It is then refereed by a editorial board of experts in that field before being accepted/rejected for publication.
  • Theses: detailed accounts of research conducted for the awarding of higher academic degrees. The research is assessed by external examiners before the degree is awarded. In many cases, it will also be later reported in a condensed form as a journal article.
  • Conferences: an important avenue for reporting new research or developments. Papers presented may or may not be subject to editorial scrutiny. Conference papers can be: not published at all, published only in abstract form, published in advance of the conference as a preprint, published in book form, or as a special issue of a journal.
  • Reports: individual publications reporting research. They may report internal research within an organization, or research done by an individual or organization under contract to a client. They can be: freely available, available only to members of an organization, only available by purchase. Sometimes the information from the report will also be published in a journal article, but more often, the report is the only source of the information.  Many governmental reports (full-text) are now being made available via the Internet.
    Patents: provides research information on new products or processes.  Once published, patent information is freely available, but rarely republished in journal articles.

Secondary Sources

Secondary sources analyze, evaluate, interpret, re-package, summarize or reorganize information reported by researchers in the primary literature. These include:

  •  Review Journals : These generally start with Annual Review of …, Advances in …, Current Opinion in …
  •  Article Reviews : Articles that summarize the current literature on a specific topic.
  •  Textbooks : These can be either specialized to a narrow topic or a boarder overview.
  •  Data Compilations :  Statistical databases (SEERS), Vital & Health Statistics, etc.
  • Article Indexes/Databases: These can be abstracting or citation (e.g. Biological Abstracts/MEDLINE).


Tertiary Sources

Tertiary sources consist of primary and secondary source information which has been collected and distilled. They present summaries of or an introduction to the current state of research on a topic, summarize or condense information from primary and secondary sources, or provide a list of primary and secondary sources of more extensive information. Examples are:

  • Encyclopedias
  • Almanacs
  • Fact books
  • Research Quickstarts/Library Course Pages/Pathfinders

    Research Chart (Primary, Secondary, Tertiary)

    Information Timeline

    When you think about how information is created and made available to the public, this gives you a good initial indication of whether a source is primary, secondary or tertiary.

        Information Timeline Chart

Just for Fun

Primary Sources in the Science Classroom - Electric Cars, Energy and Engineering

Read the full article and lesson plan:


 Photograph of first electric car

Electric auto at re-charging station, 1919

Article from 1919:  "Good bye, Horses!"

Good Bye Horses. St Paul Daily Globe, August 11, 1892.

Just for Fun


Tesla in front of Fremont Plant

2019, Tesla in front of assembly plant, Fremont, CA