A review article is an artice that reviews a topic. In other words, it provides an overview of a topic. Because they have fewer pages, review articles are on more specific topics than books, which also may provide an overview of a topic.
The following definitions refer to published, available information. The information is put in a (reasonably) permanent form.
Primary Sources are the original resources that first report research or ideas. In research, these are often research articles in scholarly journals. However, they may include newspapers, research reports, trade journals, conference proceedings, dissertations, Web sites, novels, poems, plays, speeches, interviews, letters, case studies, test data, findings from surveys, archaeological drawings, experiments, films, drawings, designs, paintings, music, sculptures, etc. IF it is the original source of information.
In science, primary literature refers to the original publication of scientific research as reported by the original researchers. These are usually published in scientific journals but may be published in government reports or publications. The distinguishing feature is that the original researcher(s) is telling the hypothesis, the methodology, the discussion and results of the research.
There is value in looking at the original report of research. You may read what the researcher says they did (methodology) and how they explain their results. You may get ideas for further research. Or you may decide you disagree with the researcher/author and you have another interpretation of the results. This can lead to discussion between experts, which can generate future knowledge.
Secondary Sources are resources that analyze, describe, and synthesize the primary or original source. These include review articles, newspaper articles, reference books such as encyclopedias and dictionaries, and textbooks.
Secondary sources include commentary about original research. The author of a secondary source can add additional insights or make connections to other research not included in the original publication.They can provide useful insights but may leave out additional information unknown to you unless you go back and examine the primary resource(s) yourself.
Secondary sources may be used to find primary sources by looking in the references of the secondary source.
This definition is a little vague. Tertiary sources are resources written about the secondary literature. In other words, literature which explains, teaches you how to use, and leads you through the vast array of primary and secondary scientific literature. Examples may include textbooks, monographs, bibliographies, encyclopedias and reference books of all kinds which provide a summary of accepted knowledge about a topic or subject area in broad outline. Librarians disagree on the precision of this definition and some do not use the term at all, preferring categories of only primary and secondary sources.
Tertiary sources can provide nice summaries of what is known about a topic. However, they usually only mention a small portion of information from the primary sources (original research publication) from which they get their information. They can be a nice start for your research but they can leave out additional useful information that allows you to properly EVALUATE the facts presented.
Tertiary sources may include primary sources in their references.
What is "grey literature?" (Or "gray.") Grey literature is information that has not been formally published and, therefore, is unavailable or hard to find. A good analogy is “as a shadow which has not yet acquired substance”. Also called “fugitive literature,” it usually refers to knowledge that is out in the world but has not yet been formally written down and distributed. For example, researchers may discuss a research study with colleagues and references may turn up in that person's paper but the original study itself is not available in a permanent form. Sometimes the information in grey literature never becomes available to you! For example, if a pharmaceutical company is researching a new drug and doesn’t distribute the information outside of its own employees because it doesn’t want to help the competition. Or a researcher never bothers to publish their research findings for some reason.
Grey literature publications include theses, conference proceedings, technical specifications and standards, non-commercial translations, bibliographies, technical and commercial documentation, government documents, and reports (pre-prints, preliminary progress and advanced reports, technical reports, statistical reports, memoranda, state-of-the art reports, market research reports, etc.). (Alberani, 1990)
The Grey Literature Report of the New York Academy of Medicine notified subscribers of grey literature publications in health services research and selected public health topics from 1999-2016. You can search their Grey Literature Collection as if you were searching a library catalog. Records of results of interest would have to be retrieved like any other book. It also listed organizations that publish grey literature.
