Primary sources are original sources of information that have not yet been filtered through analysis, examination or interpretation. They are written during the time period involved by the person(s) who conducted the research and are the result of original research or observation. Thus, primary source literature includes firsthand information on methodologies, data, results, and discussions of the findings. Primary source literature is typically published in scholarly, peer-reviewed journals.
In primary research articles:
Review articles, sometimes called literature reviews or secondary sources, synthesize or analyze research already conducted in primary sources. They generally summarize the current state of research on a given topic. Review articles can help give you a better understanding of the existing research on a topic, identify research questions you would like to explore, and find relevant sources. Review articles often:
In review articles:
Gray literature is research that is either unpublished or has been published in noncommercial forms.
Examples of gray literature include: