No abstract index was found, that is to say, no reference was found. Indexes are also called references, general checks, and readiness checks. According to the needs, the relevant matters in books, newspapers and periodicals (such as words, names, place names, titles, titles, themes, etc.). ) respectively, and indicate the source page, arranged according to a certain retrieval method, for people to consult. Generally attached to the back of related works, there are also independent books. The way to check the index of papers is as follows: Users enter the official website of WebofScience database, enter the documents they want to query in the search bar, and click the corresponding title in the search results. After clicking enter, they can see the most basic literature information such as author, abstract, publishing house and subject category. Some websites will also directly display the "Tibet Entry Number", which is the index number. However, for articles that don't display the index number, you can choose to enter the paper description details page, select "Output all records", then select "Save as HTML format", and finally open the HTML file saved in the computer, and slide down to the last page to see the contents written with the words "ISI". A string of numbers written after ISI is the index number of the paper.