What are yellow, white, blue, green, black and red?

The Blue Book is a comprehensive research report completed by a third party. The Green Paper is a research report on optimistic prospects. The red book is a research report on crisis early warning. White paper is called White paper because the cover and text of this book are white. Mainly refers to the short report published by the government. Any topic, any organization can also be used for political official statements containing background materials. The title of this book is white paper and the cover is white. When the Blue Book is used as an official document, it is a kind of diplomatic information and document submitted by the government to both houses of parliament, because the cover is blue. There is a foreign language called blue book, which is not afraid of any official documents. From the content point of view, it is reference books such as Who's Who, Guide Manual, Handbook, and even commemorative books. The list of government officials, who's who and the cover are all blue, all with the names of the blue books. Red Book Some red books are used for official documents and some are used for non-official documents. Some international organizations also use red books, such as the International Telecommunication Union Red Book. Of course, the most famous little red book with the largest circulation is the little red book, a quotation from Chairman Mao in the 1960s and 1970s. Yellow Book The Yellow Book used to refer to the important reports published by the old China and French governments, so it was named after the habit of using yellow covers.