The understanding that original research is based on first-hand data (that is, not on someone else's comments or interpretations of that data), makes it necessary to distinguish between different kinds of sources.
In this section, the difference between primary, secondary and tertiary sources is explained.
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 terms 'source' and 'reference'.
In order to use sources efficiently and in a correct manner, writers must be able to identify the nature of each source and the reason for using it. By clarifying to themselves what kind of use they make of different kinds of sources, writers will be able to distinguish between their own contribution and the argument expressed by the sources that are being used.
It should be noted that the distinctions that are made below may be more relevant in some fields than in others. Students are advised to discuss the use of sources with their supervisors and with the library staff at their 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.
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.
The University Library is a valuable resource for students in need of help concerning the choice of sources:
Primary, secondary and tertiary sources
Sources can be divided into three types, depending on their proximity to the subject of study:
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 often function as primary sources:
- works of fiction
- official documents, such as census data and legal texts
- objects, such as archaeological findings
- numeric data
Secondary sources value, discuss or comment on the primary source, or on sources analogous to the primary source that is being analysed.
The following are examples of such secondary sources:
- research articles
A tertiary source is 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. For instance, it is usually not acceptable to use compilations of facts instead of reading the original sources. Therefore, students writing essays are recommended to consult their teachers on the suitability of using tertiary sources in their writing.
Sources that would be regarded as tertiary sources include:
- study guides
- encyclopaedias and wikis
- indexes and other classification systems
A note of caution
It should be noted that the distinction between primary, secondary and tertiary sources is not a fixed one. For instance, in an analysis of an encyclopaedic article, that text would be regarded as a primary source, and in a review of a scholarly monograph, the text under scrutiny would be seen as a primary source, although it would be used as secondary source material under other circumstances.