If you are writing a research paper on a particular topic, you will have to conduct a literature search, that is, extensively read existing published papers on your area of research. You can search for peer-reviewed journal articles on your topic on Google Scholar. Using relevant keywords, you can come up with articles on your topic. You can also look for articles on your topic on the Directory of Open Access Journals (DOAJ) and SCOPUS.

Related reading:

• How should I assess scientific literature to prepare myself for writing a paper?
• Tips for effective literature searching and keeping up with new publications
• Gathering useful resources for future publication