What is the origin of the name Yuan Gui?

"Ci Fu" is the place where emperors collect books, and "yuan gui" is a turtle, which was used to deify state affairs in ancient times. It means the reference for later emperors to govern the country. Due to numerous quotations, the book has also become an important reference for later scholars to use allusions and textual research. Among them, the historical events of the Tang and Five Dynasties are the essence of Yuan Gui, and many historical materials are only seen in this book, even if they are repeated with the official history, they have collating value.