There are many types of documents, such as books, journals, dissertations, patent documents, conference documents, standard documents, technical files, etc. One of them is standard documents, whether they are international standards or national Standards all have standard numbers. For example, GB/T 7714-2005 "Rules for the Description of References at the End of the Text" is a national recommended standard, and "GB/T 7714-2005" is the standard number. Using standard numbers to search for standard documents is a good way to search.