Paragraph Structure

Each paragraph should begin with a topic sentence that acts as a thesis statement and summarizes your paragraph. If you are doing a literature review and summarizing other people's work, include the source that contains the information outlined in the paragraph. Use the active voice if possible.

Literature review and introduction

A literature review in an introduction provides an overview of past and current work in your research topic. It is usually summarized in the introduction of a thesis, and sometimes appears as a separate section. It outlines the main research questions faced in a given domain of research, and provides motivations and justifications for pursuing your research into the topic. As many students on an undergraduate level will not pursue a career in research, it's particularly important for an undergraduate thesis to understand the societal relevance of a topic and to anticipate applications of the research to "real-life" situations. Therefore, the literature review is often accompanied  by a description of the societal relevance of the research.

Literature reviews can be found in the introduction  practically in any refereed journal article. Almost every sentence in the introduction of most papers contains large numbers of citations, as the introduction summarizes the most  important facts, theories and science on which your paper rests on. You can (almost) never have to many references in an introductory literature review.

Review papers

Review papers summarize the body of research on a topic from the earliest studies right up to ongoing research. They are periodically updated as research progresses on a given topic.   A review paper is a good place to begin any study, as they put historical and current research in context, and point out when information in old papers become obsolete. They are easy to find because they are usually referenced in the introduction of most papers on the topic.

Review papers are written by leaders in this field of research, and in turn  refereed by leaders in their respective fields. These papers receive more scrutiny in the review process than other papers. Controversies on a given topic are generally described neutrally.   Often, the information found on websites can also be found in review papers. It's therefore preferable to check to see if information found on websites (which generally provide unrefereed writings) can be found in review papers. If so, it is better to use refereed papers from an established journal in your papers as reference.

Example

The following is an example of a paper with a literature review in the introduction of the paper:

Mitigating New York City's Heat Island: Integrating Stakeholder Perspectives and Scientific Evaluation
"Urbanization is often associated with elevated surface air temperature, a condition referred to as the urban heat island. Aspects of the urban environment that contribute to the urban heat island include i) dense, impervious surfaces that reduce evaporative latent heat cooling and increase the amount of energy that is absorbed and stored in the city; ii) low-albedo surfaces, such
as dark rooftops and asphalt roadways; iii) reduced skyview from within urban canyons, which impedes radiative longwave cooling to space, a process that is especially important at night (Oke 1981); and iv) anthropogenic heat sources associated with transportation and building heating and cooling systems (Taha 1997; Hsieh et al. 2007). Heat island intensity tends to be greatest at night, particularly when conditions are clear and calm. Local hot spots may shift with diurnal and seasonal cycles, under particular meteorological conditions, or with land use change (Unwin 1980). Landsberg (1981) and Oke (1987) describe urban climate and heat island processes. More recent reviews can be found in Arnfield (2003) and Grimmond (2007)."

This leads to a recent paper review paper by Grimmond (2007)

Grimmond, C. S. B., 2007: Urbanization and global environmental change: Local effects of urban warming. Geogr. J., 173, 83–88.