A [[personal knowledge management]] process. The core of the process revolves around two collections of notes - [[Reference Notes]] which summarise source material and include a link to the source, and the collection of [[evergreen notes]] which are written in the interpretive part of the process. The 20th-century German sociologist [[Niklas Luhmann]] managed to publish 70 books. He credits much of his success to his Zettelkasten, or "slip box." _Luhmann, N. (1992). Communicating with Slip Boxes. In A. Kieserling (Ed.), & M. Kuehn (Trans.), Universität als Milieu: Kleine Schriften (pp. 53–61). [http://luhmann.surge.sh/communicating-with-slip-boxes page]_ see also [[Zettelkasten project]]