A literature review is a summary of the previous research that has been done that connects to the topic being discussed. Usually it is near the beginning of a research paper, and it's purpose is to explain to the reader all of the relevant and useful previous research results that have been discovered and how it relates to the study the paper describes.
If you are creating a literature review:
Each previous piece of research is usually summarized in a sentence or two and includes an in-text citation, with a full entry in the References list at the end of your paper.
If you are searching for more sources:
Literature reviews in academic (scholarly) articles can help you understand how your topic has been studied before and lead you to previous research.
Keywords are any important word or short phrase that connect to the major idea of your topic. Keywords are useful to keep track of as you begin reading on your topic because unexpected or related ideas may help you develop your own thinking on your topic.
Ideally, you'll want to keep track of both broader and narrower keywords. Here is an example:
US Dept. of Fish & Wildlife
General broad areas ("wildlife habitat management") help you expand a search to explore what might be available.
Narrow concepts, such as the names of important people or agencies (US Department of Fish and Wildlife), key documents (like laws or policies), and specific locations (Washington) can help you focus a search that is getting too many results.
ESRI is an international supplier of Geographic Information System software, web GIS and geodatabase management applications. They also offer GIS-related information on their website, such as case studies in a variety of areas.
As another option, you can often find case study examples from the news items or reports provided by US government agencies responsible for overseeing resources of regulations in the field you are interested in. Search USA.gov for reports (you can enter a general keyword phrase like "sea level change") or by agency: