Update 'README.md'

README.md

@@ -54,6 +54,7 @@ ___
 - [Brassica Oleracea is cabbage, brussel sprouts, broccoli, cauliflower, kale](https://en.wikipedia.org/wiki/Brassica_oleracea)
 - [Wagner Group](https://en.wikipedia.org/wiki/Wagner_Group)
 - [Meng Wanzhou Extradition](https://en.wikipedia.org/wiki/Extradition_case_of_Meng_Wanzhou)
+- [Clifford Algebra: A visual introduction](https://slehar.wordpress.com/2014/03/18/clifford-algebra-a-visual-introduction/)
  
 ## [Mathematics and Theoretical Computer Science](mathematics.md)
 - [OEIS: The Online Encyclopedia of Integer Sequences](https://oeis.org/)