First, there are the primary studies that researchers conduct and publish.
Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies.
Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review.
The goal is to deliberately document, critically evaluate, and .
Literature reviews are designed to provide an overview of sources you have explored while researching a particular topic and to demonstrate to your readers how your research fits within a larger field of study.
A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories.
Your professor will probably not expect you to read everything that's available about the topic, but you'll make your job easier if you first limit scope of the research problem.
A good strategy is to begin by searching the HOMER catalog for books about the topic and review the table of contents for chapters that focuses on specific issues.
Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally that become part of the lore of field.
In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews.