https://www.gutenberg.org/ebooks/offline_catalogs.html

Perhaps you can find the information you are looking for there.

However if you plan on scraping or otherwise hitting them with a ton of traffic, consider at least to donate a good amount for the traffic you cause them. It ain't free after all.

> All Project Gutenberg metadata are available digitally in the XML/RDF format. This is updated daily (other than the legacy format mentioned below). Please use one of these files as input to a database or other tools you may be developing, instead of crawling or roboting the website.

And strongly consider a donation! (My addition)

https://www.gutenberg.org/ebooks/offline_catalogs.html#the-p...

Don't hit the site with agent. The section furtherst bottom machine readable.