Not all papers must have a literature review. However, in most academic papers, literature review is a very important part, especially when a research field or topic needs to be comprehensively sorted out and analyzed. Literature review can help readers understand the current research status, research hotspots and future development direction, and provide background and support for subsequent research issues, research methods, research results and conclusions.

When writing a thesis, whether it is necessary to have a literature review depends on the specific research problems and research fields. If there is a comprehensive and in-depth literature review in this field, you can directly quote the literature review and indicate the source when writing your thesis. However, if the literature review in this field is less or not comprehensive enough, it is necessary to review the literature by yourself when writing a paper, so as to better grasp the latest progress and research hotspots in the research field and provide support and reference for the follow-up research issues.

In a word, literature review is a very important part of academic papers, but whether it is necessary or not depends on specific research problems and research fields.