It is based upon a Kindle project [1] and initially I just used the quote library from that project (which is based on a crowd-sourced collection of quotes by The Guardian [2]).
Later, a lot of quotes have been added by kind strangers through GitHub issues and pull-requests [3].
There is this fork which has a few different languages and some other cool features. I believe the non-english quotes are mostly machine translations of the quotes in my repo.
https://literatureclock.netlify.app/?locale=pt-BR