As you begin searching through the literature for evidence, you will come across different types of publications. Below are examples of the most common types and explanations of what they are. Although systematic reviews and meta-analysis are considered the highest quality of evidence, not every topic will have an Systematic Review or Metanalysis.
Literature Reviews: An Overview for Graduate Students (by North Caroline State University Libraries)
Remember, a literature review provides an overview of a topic. There may or may not be a method for how studies are collected or interpreted. Lit reviews aren't always obviously labeled "literature review"; they may be embedded within sections such as the introduction or background. You can figure this out by reading the article.