Hello Chris,
I was re-reading some of your posts on Zettelkasten, and I find myself amazed by how many references you’ve collected.
With the aim of furthering the research, and make the list of usage examples bigger, did you know that Hannah Arendt kept a Zettelkasten? And it is digitized! She did not only handwritten cards, but also typed ones!
https://www.loc.gov/collections/hannah-arendt-papers/about-this-collection/
Here are some examples:
https://www.loc.gov/collections/hannah-arendt-papers/?q=excerpts
Have a good time!
Mikjail