When conducting a literature review, what type of information source utilizes studies written by the original researchers?

Primary sources are the original studies or research articles in which the authors report their own research findings directly. These sources present raw data, methodologies, and results directly from the researchers who conducted the study, allowing readers to understand the study's design, execution, and outcomes from the perspective of those who were involved in the research process.

This direct involvement provides the most reliable form of evidence for literature reviews because it enables critical appraisal of the original research methods and findings. In contrast, secondary sources synthesize information from primary sources, and tertiary sources provide summaries or overviews that often aggregate information from secondary sources. Peer-reviewed articles can be either primary or secondary, depending on whether they report original research or discuss prior studies. Therefore, primary sources uniquely fit the description of studies written by the original researchers themselves.