a literature review surveys scholarly articles, books and other sources (e.g. dissertations, conference proceedings) relevant to a particular issue, area of research, or theory, providing a description, summary, and critical evaluation of each work. The purpose is to offer an overview of significant literature published on a topic. http://guides.library.ucsc.edu/write-a-literature-review
A good literature review will be well focused on the specific research question. The sources used will be currrent, relevant, authoratative, accurate, and from an unbiased perspective.