Primary, secondary and other source types

Primary sources provide direct or original evidence in relation to the question you are investigating. They may record an event, present original research or be the material you are analysing.

Examples include:

• journal articles reporting original research
• research data, surveys and interview transcripts
• legislation, court judgments and official records
• letters, speeches, diaries and archival documents
• novels, films, games, artworks and performances
• source code, patents and technical designs
• photographs, recordings and social media posts

Use primary sources when you need to examine original evidence, data, ideas, experiences or creative work directly.

A primary source is not necessarily accurate, neutral or reliable. You must still consider who created it, why it was created and what its limitations are.

Secondary sources interpret, analyse, evaluate or synthesise primary sources and original research.

Examples include:

• review articles and evidence syntheses
• academic books discussing existing research
• critical essays and commentaries
• biographies and historical accounts
• legal textbooks and case commentaries
• articles analysing games, films, literature or artworks
• research reports that bring together evidence from several studies

Use secondary sources to understand existing interpretations, compare arguments, identify debates and place primary evidence in context.

Secondary does not mean less important. Many assessments rely heavily on secondary academic research.

Tertiary sources compile, organise or summarise information from primary and secondary sources.

Examples include:

• encyclopaedias
• dictionaries
• handbooks
• bibliographies and indexes
• introductory textbooks
• subject overviews

Tertiary sources can help you understand an unfamiliar topic, identify terminology and find further sources. However, they may not provide the depth or original evidence required for detailed academic analysis.

Academic or non-academic describes how and for whom information was produced. Primary, secondary and tertiary describe the role that information plays in relation to your research question.

This means that a source can fit more than one classification.

Ask what role the source plays in your work rather than deciding from its format or title alone.

For example, a journal article reporting an experiment is usually a primary research source. A journal article reviewing several experiments is secondary. Both are academic sources, but they perform different functions.

Grey literature is information produced outside conventional academic or commercial publishing. It is often created by governments, public bodies, charities, professional organisations, researchers or businesses.

It can include:

• government and policy reports
• technical reports
• professional guidelines
• working papers and preprints
• research reports
• consultation documents
• conference abstracts, posters, presentations and unpublished papers
• standards and specifications
• theses and dissertations
• reports produced by charities, think tanks or industry bodies

Conference material varies. Formally published conference papers may be peer-reviewed academic sources, while abstracts, posters, presentations and unpublished papers may be grey literature. See the Library’s Conference proceedings page for help finding and using them.

Grey literature can provide current, practical or specialist information that is not available in academic journals. It is particularly useful for policy, professional practice, technical subjects and emerging areas of research.

Grey literature is not automatically academic or non-academic, primary or secondary. Its classification depends on who produced it, what it contains and how you are using it.

Quality and transparency vary. Check:

• who produced and funded it
• why it was created
• whether its evidence and methods are explained
• whether its claims can be checked
• when it was published or updated
• whether the organisation may have a particular interest or position

Use Evaluate sources to assess whether grey literature is credible, relevant and appropriate for your work.

Terms such as online and audiovisual describe a source’s format, not its role in research. A website, podcast, video or social media post may be primary, secondary or tertiary depending on its content and how you use it.

Similarly, case study can describe a research method, a published report or a teaching resource. Look at what the case study contains and the role it plays in your assessment.

Subjects use and describe sources in different ways. The following examples illustrate some common approaches, but your assessment brief and tutor should take priority.

• Psychology, biosciences, sport and other research-based subjects: an article reporting an original study is usually primary research. Review articles and systematic reviews are secondary sources. Datasets and official statistics may be primary evidence.
• Law and criminology: legislation and court judgments are primary legal sources. Textbooks, journal articles and case commentaries are usually secondary sources. Government policy documents may be primary when the policy itself is being examined.
• Computing, cybersecurity and engineering: source code, technical designs, datasets, patents and vulnerability disclosures may be primary sources. Technical analysis and research reviews may be secondary. Standards and vendor documentation can provide important professional or grey literature.
• Business and accounting: annual reports, financial statements, company communications and market datasets may be primary evidence. Industry analyses, biographies and academic case analyses are normally secondary.
• Games, computer arts and other creative subjects: games, artworks, films, performances and design artefacts may be primary sources when analysed directly. Critical writing and research about those works are secondary sources.

The same material may be classified differently when the research question changes. A news article is secondary if you use it to learn about an event, but primary if you are studying how the media represented that event.

There is no single correct balance of primary, secondary and tertiary sources for every assessment.

Start with:

• your assessment brief
• the marking criteria
• your reading list
• guidance from your tutor or supervisor

Consider what you need the source to do:

• use primary sources when you need original evidence, data or material to analyse
• use secondary sources when you need interpretation, analysis, context or synthesis
• use tertiary sources to gain an overview, identify terminology or find further sources
• use grey literature when you need appropriate policy, professional, technical or current information

Primary sources are not automatically better than secondary sources. A strong assessment often uses different source types for different purposes.

Before selecting a source, ask:

• What kind of evidence does the assessment require?
• Do I need original material, an interpretation or a general overview?
• Does this source support the specific point I want to make?
• How is this type of source understood in my subject?
• Have I evaluated its relevance, authority, evidence and currency?

Once you know what kinds of information you need, use Search effectively to choose appropriate search tools and develop your search.