Yes, the review paper does not involve data collection, so it is reasonable to quote the data of existing literature. As for the citation ratio, there is no agreed requirement in the industry, and everything is subject to the journal guide.

If it is a narrative review, it is no problem to summarize the existing research results, but the main purpose of the article is to critically analyze the research problems, not simply summarize them.

If it is a systematic review, the main body of the article should include specific methods. In this part, you need to mention the inclusion and exclusion criteria, interpretation methods, models and/or theories, the support provided by a paper, the research for or against the argument, and so on.

Extended data

According to the number of original documents collected, the degree of refining and processing, the form of organizational writing and the level of academic level, reviews can be divided into three categories: inductive, general and critical.

(1) summary:

Inductive summary is an organized, systematic and logical academic paper written by the author by sorting and summarizing the collected documents and arranging them in a certain order to make them interrelated and coherent. To some extent, it can reflect the current research progress of a certain topic and a certain field, but few authors have their own opinions and opinions.

(2) General review:

The general introduction is a systematic and logical academic paper written by an author with a certain academic level on the basis of collecting more materials, which can express the author's views or tendencies. Therefore, this paper has certain guiding significance and reference value for readers engaged in this topic and this field.

(3) Critical review:

Critical review is an author with high academic level and high attainments in this field. On the basis of collecting a large number of data, the original data are summarized, analyzed and written to reflect the current research progress and development prospects in this field. Because the paper is logical, there are many authors' opinions and comments.