diff --git a/README.md b/README.md
index 5b15cc817f62b2241f48122f0708cc5cc37fb58f..ca89a097a8cfb3f3407c22af4cce699149b9afbf 100644
--- a/README.md
+++ b/README.md
@@ -46,11 +46,13 @@ https://www.youtube.com/watch?v=dS5kwdaNhZo
 <img src='img/k-factor.png' width=300px>
 
 * Thickness
-* K-Factor
-* Relief
+* <a href='https://www.hawkridgesys.com/blog/sheet-metal-understanding-k-factor/'>K-Factor</a>
+* <a href='http://files.engineering.com/download.aspx?folder=b0283dfb-f6a8-4c7c-8207-eb6510b27548&file=Sheet_Metal_Design_Considerations.pdf'>Relief</a>
 
 ### Design tools
 
+<img src='img/fusion-sheet-metal.png' width=300px>
+
 * Fusion 360 sheet metal: 
 	* <a href='https://www.youtube.com/watch?v=nEjFMYNGY4g'>tutorial (nyc cnc)</a>
 	* <a href='https://www.youtube.com/watch?v=1aDN44__L9E'>tutorial (cardboard)</a>