@inscript @flancianKonrad Gessner is one of the more interesting and influential slip users.For the early 20th century influences try Antonin Sertillanges, Paul Chavigny, and Beatrice Webb.https://hyp.is/hqaHQDq_Eeyx-Nd3_QncSw/en.wikipedia.org/wiki/Zettelkasten

Antonin Sertillanges' book The Intellectual Life is published in 1918 in which he outlines in chapter 7 the broad strokes a version of the zettelkasten method, though writing in French he doesn't use the German name or give the method a specific name.[11] The book was published in French, Italian, and English in more than 50 editions over the span of 40 years. In it, Sertillanges recommends taking notes on slips of "strong paper of a uniform size" either self made with a paper cutter or by "special firms that will spare you the trouble, providing slips of every size and color as well as the necessary boxes and accessories." He also recommends a "certain number of tagged slips, guide-cards, so as to number each category visibly after having numbered each slip, in the corner or in the middle." He goes on to suggest creating a catalog or index of subjects with division and subdivisions and recommends the "very ingenious system", the decimal system, for organizing one's research. For the details of this refers the reader to Organization of intellectual work: practical recipes for use by students of all faculties and workers by Paul Chavigny [fr][12]. Sertillanges recommends against the previous patterns seen with commonplace books where one does note taking in books or on slips of paper which might be pasted into books as they don't "easily allow classification" or "readily lend themselves to use at the moment of writing."