Citation refers to articles or books that cite other people's published research results in academic papers, research reports and other academic works. Cited documents can include books, periodicals, papers, reports, patents and other different types of documents, and can also include electronic documents on the network, such as web pages, databases, e-books and so on. In academic papers or reports, the way to quote other people's research results is generally to insert the notes of the cited documents in the text, such as the author's name, publication year, page number, etc., so that readers can trace back to the specific citation source. Literature citation is also one of the important criteria to judge the quality and credibility of an academic paper or research report.