A Zettelkasten is a method of note-taking pioneered by Conrad Gessner and famously used by Niklas Luhmann.1 The concept revolves around gathering Atomic notes in a slip box (or a digital equivalent), each uniquely described by an ID. These IDs can then be used as referrals or Bi-directional links between notes. In its simplest form, a Zettelkasten is a graph where the nodes are notes and the connections are links. The appeal of this process is that connections between knowledge - often never found elsewhere - appear dynamically, allowing for a deeper connection with the topic at hand.
Here is test Bibliography.
IDs
The IDs used to identify your notes can be whatever you prefer, as long as they are unique. The preferred method for a physical Zettelkasten is to use numbers based on the date and time (e.g. 202003202350). For software-based Zettelkasten, one could just use the title of the note or a randomly generated ID (like the one in the URL of this page).
Wikipedia contributors. (2021, March 16). Zettelkasten. Wikipedia. https://en.wikipedia.org/wiki/Zettelkasten