Academic search engines: Through academic search engines, such as Google Academic and Baidu Academic, a large number of academic papers and documents can be searched. In the query results, you can check the similarity index of the papers and understand the repetition rate of the papers.

Paper duplicate checking websites: There are many professional paper duplicate checking websites, such as paperfree and papertime, which can provide duplicate checking services. You can upload papers on these websites and check them according to the requirements of the websites. These websites usually analyze the text, content, quotations and so on of the paper, and give the corresponding repetition rate results.

Library or institutional knowledge base: If your school or institution has library or institutional knowledge base resources, you can ask whether the library or institutional knowledge base provides duplicate checking service for papers. These services usually use professional duplicate checking software or algorithms to detect the repetition rate of papers.