How to take smart notes by Sönke Ahrens
This book is based on the Zettelkasten/Slip-box method by Niklas Luhmann, a German sociologist who wrote over 70 books and nearly 400 academic articles. Zettelkasten method provides us an external system for us to think with and manage our knowledge. Learning is consists of reading, thinking, and writing. Therefore, it is essential to know how to take notes, make connections between them, and the way to retrieve them.