Secondary sources are compiled or produced from information originally reported in primary sources. This means they come second in the publication cycle. Secondary sources may summarize a single piece of research, provide a general overview of a topic, or review a collection of research on a specific topic over a period of years. Secondary sources (e.g. books) tend to be written in a more generalized language that most readers can understand.
Review articles are a specialized type of secondary source in the sciences that are often published in journals containing mostly primary research articles. These review articles may provide critical analysis, interpretations, discussions, or reviews of original research. They may discuss emerging trends in a research area, or discuss some of the controversial issues related to a particular field of study, or note inconsistencies in research findings.
Because a review article does not report new data or information, it is considered a secondary source. Review articles will not include a methods, results, or discussion section. Nonetheless, this type of review article serves an important function in providing overviews of research in a specific area.
Types of secondary sources in the Sciences: