Here's an example of an exploration tool built using the content of books: https://books.archivelab.org/dateviz/ https://books.archivelab.org/dateviz/ It would

Here's an example of an exploration tool built using the content of books: https://books.archivelab.org/dateviz/ https://books.archivelab.org/dateviz/ It would be nice if anyone could build such tools, but all of that data is locked up inside of places like Google Books and Hathi Trust. Google isn't even interested in making their metadata available, other than by running searches.