2. Types of Information

Before introducing you to various types of information, it should be noted that a general distinction can be made between primary, secondary and tertiary sources. Depending on the object of study, such sources are sometimes referred to as primary, secondary or tertiary literature. Defining sources as either primary, secondary or tertiary causes some difficulties, as the way a source is treated within different contexts varies. To get a basic understanding of the classification, let’s consider these definitions:

• Primary sources provide first-hand information that is closest to the object of study (e.g., publications on original research, numerical data, transcripts or photographs).
• Secondary sources provide non-original data that are for example summarized or synthesized (e.g., literature reviews, textbooks, newspapers, magazines).
• Tertiary sources index primary and secondary sources (e.g., encyclopedias, dictionaries, almanacs).

When using information in your own work, be aware that you should always aim to refer (see section on referencing) to primary sources. This way you force yourself to verify where information originates (thus reducing the chance you for example use incorrect statistics or outdated conclusions), and you make your work verifiable for the reader.

Most academic material is created within the scholarly communication infrastructure, through academic publishing (via for example Elsevier or Springer Nature). In addition, grey literature is published via other channels. A classification can be made as follows:

• Academic publishing is characterized by peer-review, a concept in which scholars assess the quality of manuscripts submitted by researchers in the same field. Usually, peer-review is double- or single-blinded, meaning the reviewers cannot be identified by the authors who submit the manuscript and vice versa (in case of the double-blinded). Peer review is considered necessary to academic quality, even though it cannot entirely prevent invalid research and has at times failed to recognize high-quality work.
• Grey literature encompasses material that is published by organizations other than academic publishers. Examples are technical reports, government documents, white papers, working papers, newsletters, speeches, etc. As grey literature is not necessarily subject to critical objective evaluation before it is published, it is important to evaluate such sources of information on for example reliability and potential bias.

The usefulness of the materials discussed above differs per field of study. In fundamental sciences – such as physics - the focus will mainly be on peer-reviewed academic literature, whereas in more applied fields - such as Civil Engineering – grey literature can be a very useful source of information. Advice on when various types (grey) literature can be of use is given below.

A (scientific) journal is a periodical publication that reports new research findings, most commonly in the form of articles that are written and reviewed by researchers working for academic institutions. To maintain a high academic quality and to prevent the publication of invalid research, journal articles are peer-reviewed by experts in the field the article is about. Some common types of articles published by journals are:

• Original research: report of original findings and ideas, usually including abstract, introduction, methods, results, discussion, and conclusion sections.
• Clinical study: a detailed publication on the methods and results of a clinical trial (experiments or observations done in clinical research).
• Review article: an analysis of existing published literature in a specific field.   

When to use: journal articles are a very informative and trustworthy sources to refer to when writing about or studying a topic. Original research and clinical studies are examples of primary literature, that you can refer to directly when writing about the ideas and findings presented in it. Review articles are regarded as secondary literature, as they analyse primary literature. This means you should refer to a review article only when writing specifically about the new insights - gained from studying primary literature - presented in that review article.

Where to find: titles, abstracts and more information (but no full text) about journal articles are indexed in literature databases such as Scopus or Web of Science, which can be accessed via Databases A-Z. Search engines, such as Google and Google Scholar, can locate articles at publisher websites or in archives/repositories. The full text of journal articles is available at those publisher websites (sometimes behind a paywall) and in archives/repositories.

Conference papers are contributions submitted to conferences (events where researchers present and discuss their work), often included in the conference proceedings published by the organizers of the events afterwards. Conference papers take on similar forms as journal articles. Adapted versions of conference papers (with new/more elaborate information) can be submitted to journals, and ultimately be published as a journal article.  

When to use: conference papers usually are informative and trustworthy sources to refer to when writing about or studying a topic. When searching for the most recent findings, conference papers can be a great source, as many journal articles present findings with a significant delay due to the long(er) publication process. If you doubt the quality of a conference paper, you can look up the conference website or publisher website to see if the work has been peer-reviewed.

Where to find: many peer-reviewed conference papers are indexed in literature databases such as Scopus or Web of Science, which can be accessed via Databases A-Z. The full texts of those conference papers are available at publisher/conference websites (sometimes behind a paywall). Conference papers are also commonly uploaded to university repositories. If the content of these repositories is indexed by Google, the conference papers can be found via Google Scholar.

Monographs and edited volumes are very detailed scholarly pieces of writing on a specific subject. When such a work is written by a single author, it is referred to as a monograph. When each chapter is written by a different (group of) author(s), it is referred to as an edited volume (or edited collection).

When to use: monographs and edited volumes contain valuable information when doing research on a topic in depth.

Where to find: academic research databases and FindUT index monographs and (chapters of) edited volumes. To make use of these databases and FindUT, access them via them via Databases A-Z.

Reference sources (also called background sources or resources) include dictionaries, encyclopedias, atlases, almanacs, directories, handbooks, and bibliographies.

When to use: you can use reference sources to get an overview of a topic, or to quickly find very specific information. Reference sources are regarded as tertiary literature, meaning that when referring to information presented in a reference source in your own academic writings, you usually have to look up the primary literature it is based on.

Where to find: to make use of reference sources paid for by the University of Twente, make sure you access them via Databases A-Z or the Guides per Discipline. The latter lists relevant reference sources per study programme. Freely accessible reference sources, such as Wikipedia or Collins Dictionary, can be found via for example Google.

Text books contain a compilation of content organized in a way that allows readers who are relatively new to a topic to learn about it. Text books are used mostly in educational institutions.

When to use: text books come in handy when you seek to understand the fundamentals of a topic. They are often regarded as secondary literature, meaning that when referring to information presented in a book in your own academic writings, you usually have to look up the primary literature it is based on.

Where to find: although some text books are publicly available, access to most needs to be paid for. To access all the books in the collection of the University of Twente, you can use the discovery tool FindUT.

An exclusive right to prevent others from using or selling an invention, granted to the inventor by a government. A filed patent contains – among other things – a description and drawings (if necessary to understand the subject matter) of the invention. Patents are territorial rights, applying to for example the Netherlands or the US, and are granted for a limited period.

When to use: for study or research related goals, searching patents can for example help you identify business activities, find experts in your field of interest and discover new research areas. When you intend to apply for a patent, a ‘novelty search’ can be carried out to determine the extent to which your invention already exists.   

Where to find: Electronic copies of issued patents, as well as patent applications are indexed in search engines of patent and trademark offices. Espacenet is one of the largest free search engines for patents from countries around the world, allowing you to search in the indexed abstracts and download the full-text. Espacenet can easily be accessed via Databases A-Z.