Generally, there are no footnotes in the references of the paper, because the references are mainly used to list other related documents cited in the paper to prove the credibility and academic value of the paper. If you need to add footnotes, it is suggested to explain them in the text or footnotes of the paper.

If you want to add some extra information or comments to the references of the paper, you can consider adding them in brackets or square brackets after the references. For example, when quoting a journal article, you can add some comments after the author, article title, journal name, publication year, page number and other basic information, and enclose them in brackets or square brackets, as shown in the following figure:

Smith, J. (20 10). The title of the article. Journal name, volume (issue) and number of pages. (This article deeply analyzes ...)

In this example, the words in brackets indicate comments or supplementary explanations to this article.

It should be noted that if annotations are added to references, they should also follow the corresponding format specifications and requirements, and keep them unified and standardized. At the same time, the content of the notes should be concise and accurate, which is related to the theme and content of the paper.