a. Original articles (original research articles, case reports/case series, and technical notes)
These are detailed studies reporting original research and are classified as primary literature. They include hypothesis, background study, methods, results, interpretation of findings, and a discussion of possible implications.
b. Review articles
Review articles provide a critical and constructive analysis of existing published literature in a field, through summary, analysis, and comparison, often identifying specific gaps or problems and providing recommendations for future research. These are considered as secondary literature since they generally do not present new data from the author’s experimental work. Review articles can be of three types, broadly speaking: literature reviews, systematic reviews, and meta-analyses.