First, the content query of ancient books; Second, the query of the ancient book version.
The former kind of rain and sadness was mentioned in 03, but it was not very detailed. The contents of the inquiry book can be found on the ancient books inquiry network. Such famous books are The Complete Collection of Ancient Books in China, Ancient Books in Han Dynasty and China Ancient Books Network.
The latter can be found in the online data book inquiry of major libraries, and all provinces and cities in China have their own online ancient book inquiry systems, such as the online public catalogue inquiry system of the National Digital Library of China. Then there are more professional websites about ancient books identification, introduction, learning and exchange, such as: ancient books bar, book collection network, book collection forum, Buyi, Tianya community, Confucius and so on. Good luck!