This was written by Timothy Snyder:
http://history.yale.edu/people/timothy-snyder

This text is from the version published here:
https://qz.com/846940/a-yale-history-professors-20-point-guide-to-defending-democracy-under-a-trump-presidency/

The short post version was expanded to a book:
https://www.amazon.com/Tyranny-Twenty-Lessons-Twentieth-Century/dp/0804190119