Different kinds of sources

For writers who make use of previous research, it is important to be able to distinguish between different kinds of sources and knowing whether they are useful or not. If you are a student and have been asked to locate sources for an assignment, for instance, you need to know what kinds of sources you have found in order to know if they can be used.

On this page, we explain different kinds of sources and how to find out whether they are reliable or not.

Source and reference

The source is the text or other work that provides the information that is being used, whereas the actual mention of the source that is being used is called a reference. To some extent, these terms are synonymous; in several reference styles, the list of sources used in an academic text are called References, for instance. When discussing the actual function of the reference in the written text, however, it may be useful to distinguish between the two terms.

In order to use sources efficiently and in a correct manner, you must be able to identify the nature of each source and the reason for using it. By clarifying to yourself what kind of use you make of different kinds of sources, you will be able to distinguish between your own contribution and the argument expressed by the sources that you use.

It should be noted that the distinctions that are made below may be more relevant in some fields than in others. If you are a student, discuss the use of sources with your supervisors and with the library staff at your departmental library. Note, though, that all writers need to be aware of the importance of originality, in the sense of first-hand results, in scholarly writing.

Common types of publications

Research writing is published in various forms. Depending on discipline, some publications forms are more common and relevant than others. Here we list some common types of publications:

Anthology / edited volumes

An anthology (or edited volume) is a collection of texts (or other created works) on a specific subject that are published (or otherwise presented) together. Usually, the different chapters in the book will be written by different authors, and there will be an introductory chapter written by the editor(s), providing a general introduction to the contents of the book.

Conference proceedings

Volumes consisting of papers presented at a conference are often referred to as conference proceedings. Such publications usually consist of articles based on the plenary lectures and on a selected number of conference presentations.

Journal / Periodical

A journal (or periodical) is publication that is issued regularly (periodically = 'at regular intervals').

Journal article

An article is a text that has been published in a journal (periodical), magazine or newspaper. There are different kinds of articles; apart from original articles (articles that present new, original, research), there are review articles, letters and editorials, for instance. Original articles can be divided into, for instance, methodological articles, theoretical articles and case studies. For further information about different kinds of articles, see


A monograph is a text (often book-length) that treats one specific subject.

Thesis / Dissertation

A thesis (dissertation) is an extensive research paper that is written as partial fulfilment of an academic degree.

Thesis of dissertation? Most reference style manuals have been published in the US and therefore use the American English 'dissertation' for 'doctoral dissertation,' whereas the word 'thesis' or 'doctoral thesis' is more common in British English.

How to choose sources

One of the central learning outcomes of university studies is the ability to assess information. When writing, students train their ability to decide whether a source is appropriate and how to use it. Read more here:

Remember that LU Libraries provide valuable resources for LU students in need of help concerning the choice of sources. Faculty and department libraries provide support geared to students' subject areas.

Primary, secondary and tertiary sources

Sources are sometimes divided into three types, depending on the way in which they relate to the subject of study:

Primary sources

A primary source is usually a document or result that is being reported first hand. In other words, primary sources are original sources, not interpretations made by someone else. The following kinds of texts/sources often function as primary sources:

  • works of fiction
  • diaries
  • interviews
  • official documents, such as census data and legal texts
  • artefacts, such as archaeological findings
  • numeric data, such as statistical data
  • corpora, such as large collections of texts or recordings of speech
Secondary sources

Secondary sources are texts that value, discuss or comment on primary source materials. Previous research in the field is often defined as secondary sources. The following are examples of such secondary sources:

  • research articles
  • biographies
  • monographs

Tertiary sources

A tertiary sourceis a source that summarises or compiles facts and knowledge produced by someone else. Tertiary sources are often some kind of assemblage of primary and secondary sources. They are convenient for quick access to summarised facts, but not all sources that belong to this category are considered suitable for scholarly writing. In most cases, it is not acceptable to use compilations of facts instead of reading the original sources, for instance. Therefore, students writing essays are recommended to consult their teachers and library on the suitability of using tertiary sources in their writing. Sources that would be regarded as tertiary sources include:

  • textbooks
  • study guides
  • encyclopaedias and wikis
  • indexes and other classification systems

A note of caution

The distinction between primary, secondary and tertiary sources is not a fixed one. For instance, in an analysis of an encyclopaedic article, that article would be regarded as a primary source, whereas it in another context would be seen as a tertiary source. Students are advised to check with their teachers what types of sources are expected and accepted.

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