Anyone read Porstmann's Kartei - Kunde: das Handbuch der Karteitechnik?
I've come across Porstmann a few times as the "intellectual father of the A-Series", the "creator of the DIN formats", and the creator of A4 in various contexts. I saw that he wrote an interesting looking handbook in the mid-1920s and was curious if anyone has come across or even read it? It looks like it went into three editions up to the 1950s. I'm not seeing any English translations at present. I suspect it has material on using card indexes as databases and may be focused on business use, but may also have some connections to note taking practices of the time. I've also found several references to Porstmann's work and that of George Christoph Lichtenberg which makes me even more curious about the potential note taking connections.
Porstmann, Walter. Kartei - Kunde: das Handbuch der Karteitechnik. Stuttgart: Verlag für Wirtschaft und Verkehr, 1928. https://search.worldcat.org/formats-editions/58666432?limit=50&offset=1&orderBy=publicationDateAsc