In many research papers, after the introduction, there's a literature review section, especially if more background and context information needs to be presented. While this type of information was briefly discussed in the introduction, sometimes more in-depth information is also required to prepare your reader for the upcoming sections, e.g., methods, results, and discussion. (Note that sometimes, papers only include background information in the introduction, without having a literature review, but the introduction would be a bit longer then. As you're writing a systematic review, you also may or may not have one. You can discuss this more with your mentor.)
Considering what you will add in this section, you would be more systematically analyzing and synthesizing existing research on your topic. This section is also important given that you need to demonstrate research ability, as well as how experienced you are in the topic you're investigating.
It's important you provide the most recent and credible "literature" review, mentioning the prevalent theories. You need to look at the most prevalent current studies related to your topic and evaluate and compare these studies, and if there are any gaps identified, you should mention these too. You overall need to make your reader fully understand what you're doing, while conveying to them that you're a reliable author.
You now understand the importance of the section, yet many get it wrong and thus write it wrongly. There's a major difference between a literature review and something called "annotated bibliography," where in annotated bibliography, writers essentially provide a summary and evaluation of each article or resource, but in a one-by-one approach, with no connection between those many articles.
A literature review is fundamentally different from this, where you need to synthesize and compare different pieces of information in various studies. While you're sort of summarizing existing research, it shouldn't be a mere or simple summary. It’s important to understand that you are required to provide critical analysis and synthesize relevant scholarly work. Another important point is that your section doesn't state, prove, or develop any main points, as it's not a research paper on its own.
According to San José State University, there are three types of literature review organizations. The types are: chronological, thematic, and methodological.
Chronological organization is organizing the resources you used based on when they were published, or more of when specific developments happened. You may use this if events' sequential order would serve the context or is important for any reason. Through this type, it's like you're describing how knowledge evolved over time. For instance, if you're writing a literature review on sperm whales, you may firstly begin with British biological studies from the 18th century, move on to Herman Melville's Moby Dick (1851), then discuss a book on sperm whales in art (1968), then include biology articles from the 1980s, and finally end with recent research on American whaling practices of the 19th century. You can see that this approach provides something similar to a timeline on how perspectives on sperm whales evolved.
Thematic organization groups sources based on themes or topics. If you considered this like organizing books in a library, thematic would be by subject, unlike chronological which would be by publication date. You may be more inclined to use this type if you're going from general themes to more specific ones. An example is you may be investigating education, then narrow it down to higher education, and finally to writing centers.
Getting back to the sperm whales example, using thematic organization, you may be organizing the sections based on how they're portrayed in cultural documents. You may firstly look at texts that examined the "personification" of sperm whales; this means you would see how they're often given human traits in literature/arts. Then, you would be moving into a different theme; for instance, you may be looking at sources that discuss the exaggerated proportions of sperm whales. You may be describing how their size and power have been overstated in historical accounts. In the third section, you may research misunderstood behaviors about sperm whales.
Unlike chronological and thematic organization, methodological organization isn't based on reviewed material content, but on the methods you used. It focuses on how the researcher approached the topic rather than what was found. You would use this type of organization if the methods you used are the most important.
An example to make it clearer is if you're doing research on different drug abuse treatment studies. You may be grouping studies by how they did the study, their methodological approaches: longitudinal studies, case studies, randomized controlled trials, etc.
Now that you know all of this about literature reviews, it's time to know how to systematically write them. We'll be examining the following steps, which is guided by the University of California, San Diego.
However, before proceeding, you need to know that sometimes, full articles may only be literature reviews, not only sections in research papers or whatever. Thus, the following would work for both literature reviews that are part of larger articles and those that are full-length articles that are themselves literature reviews. You can also see some similarities between the procedures here and those you do when initially starting your research process, as defined earlier in the curriculum.
Before you start doing the research, it is perfectly reasonable that you need to know what you are doing research about. Thus, it is essential you have a very clearly and specifically defined research question or problem. At this point, you need to identify the keywords you'll be using to search your relevant research.
The next step is to actually conduct your literature search, where in this stage, you usually use a range of keywords to find the most relevant articles you're looking for. You should be using credible databases, e.g., PubMed, Web of Science, JSTOR, PsycINFO, Cochrane, etc. Your main and first priority is to look for peer-reviewed and scholarly articles, as agreed on, given that as mentioned, those are the gold standard of research. However, you may also use published books. (Refer to "Scholarly Work.") Now you should read through the obtained/yielded titles and abstracts and select and save articles. (More on this is discussed in "How to do research.")
The third step is to "Absorb as much information as you can." From the previous step, your search has yielded a number of different studies. Now it's time to read through those resources and take notes on them. While it's not like extensive note-taking when you're studying in your biology coursebook in high school, you should include anything that you think is helpful to you in your thinking about the topic. This may include different and important ideas, key points, and even page numbers that index important information for your review. (More information presented on this in "How to Search" and "How to Read a Paper.")