Reference #1: How To Take Smart Notes
The ongoing creation of a Zettelkasten is described in three steps. First, make a note of any idea which occurs to you — these are called "fleeting notes". They are collected in inbox until you have time to process them.
Second, while reading if you come across something insightful or that you don't want to forget, take a "literature note". Write the content in your own words on one side of a card, write bibliographic information on the other, then store in your reference system.
Finally, review the notes you've created — ideally no more the a few days after writing them — and think how they relate to your interests. For each idea, thought, or discussion, add a permanent note to you Zettelkasten.
Ahrens. How To Take Smart Notes, 2017. (23-24)