Blue Textbook
This is a book with a blue cover, and its name is "Blue Book".
The blue book in the early days mainly refers to a kind of diplomatic materials and documents submitted by the British government to the two houses of parliament. Because the cover is blue, it is called the blue book. Later used to refer to some official documents, usually representing the views of scholars or the academic views of research teams.
Of course, in addition to representing official documents, this emoji can also be used in topics related to reading, writing, learning, and school education.
