In the morphological evolution process of Chinese ancient books, it was a fundamental shift from scrolling to folding. The shift is closely related to the invention of the printing press and its application, and it has become a widespread reality during the mid and late Tang Dynasty period. The related records could be found in Yun Xi You Yi, Old Tang Shu and New Tang Shu. The high appearance frequency of the word, correspondence, in the poems in mid and...
