Primary sources on Luhmann's system

Sukhovskii

This is my attempt to account for primary sources on Luhmann's zettelkasten, not secondary resources. Have I overlooked anything? I would appreciate any additional insights.

1. The slip box itself implicitly contains the techniques of work. However, extracting and analyzing these techniques is not an easy task.
2. Inside of Luhmann's Zettelkasten there is a series of entries on the principles of note-taking.
3. Luhmann's system theory has many parallels with his understanding of Zettelkästen, as the slip box is also a system.
4. The article “Kommunikation mit Zettelkästen. Öffentliche Meinung und Sozialer Wandel.” Here, Luhmann openly shares his thoughts on the nuances of the system.
5. Luhmann's insightful interview with Dirk Baecker and Georg Stanitzek in the book “Niklas Luhmann. Archimedes und wir Interviews” delves into his writing practices.
6. Another interview that delves into Luhmann's working style is his conversation with Wolfgang Hagen in “Warum haben Sie keinen Fernseher, Herr Luhmann? Letzte Gespräche mit Niklas Luhmann.”
7. There's a three-minute segment in the documentary “Niklas Luhmann - Beobachter im Krähennest” where Luhmann showcases his system.
8. There are almost certainly scattered memories of Luhmann's students and colleagues. He told many people about his Zettelkästen.