A literature search is one of the most important steps in scientific research. It refers to the systematic process of searching for published scientific studies, articles, guidelines, books, and evidence related to a specific research topic. The purpose of a literature search is to understand the current state of scientific knowledge, identify research gaps, avoid duplication of previous work, and support the scientific foundation of the study.
Researchers perform literature searches before starting almost every type of research project. A proper literature search helps researchers determine whether the topic has already been studied, what methodologies were previously used, what limitations existed in earlier studies, and which unanswered questions still require investigation. Without a strong literature search, researchers may unintentionally repeat already published work or design studies with weak scientific justification.
A good literature search should be organized, systematic, and focused. Researchers usually begin by defining the main research question and identifying important keywords related to the topic. Synonyms, medical subject headings, abbreviations, and alternative terms are often included to improve search sensitivity and retrieve more relevant articles.
Several scientific databases are commonly used during literature searching. Among the most important databases are:
Each database has different strengths. PubMed is widely used in medical research, Scopus and Web of Science are useful for citation analysis, Cochrane specializes in evidence-based medicine and systematic reviews, while Google Scholar provides broader academic coverage.
One of the most important skills in literature searching is the correct use of keywords and Boolean operators. Boolean operators help researchers combine search terms more effectively:
For example:
“migraine AND vitamin D”
will search for studies containing both terms.
Another example:
“obesity OR overweight”
will retrieve studies containing either term.