Just found out via a german DSLR-forum that someone writes a book about darktable 3 in german language.
Title: That’s how it works in darktable 3
Subtitle: import, edit and manage photos
It will be released about march 2020 in the dpunkt.verlag, one of the bigger publishing companies in germany.
Description: Enough from software-abos? Learn the handling of darktable 3 and realise your complete workflow with the free image editing software. All relevant function are explained with examples, from installation to the editing and management techniques.
The author is computer scientist and published some books about astronomy before.