You are being asked to locate and use articles that are "empirical research". Empirical research uses data derived from actual observation or experimentation.
To determine if an article is an empirical research article, use these guidelines (from USF's guide listed below):
Here are some resources that explain what empirical research is.
Empirical Article: Research articles describe and document research conducted by the author(s). Empirical studies are based on data derived from observation or experimentation. Research articles usually comprise an abstract, introduction, methodology, results, discussion, list of references and appendices.
Literature Review: An article in which the authors present the findings of other scholars studies. A literature review identifies major scholars and studies in a particular research area, summarizes current findings and provides a robust bibliography.