diff --git a/assign4/README.md b/assign4/README.md
index dab475b9fe21884de0762bf9faea8c457657dd3b..3e93d6966917443d1a6fd821c6597fce9bb63daa 100644
--- a/assign4/README.md
+++ b/assign4/README.md
@@ -95,7 +95,7 @@ that exports location info through bound variables.
 **Important**: Please avoid the usage of UIKit, MKMapView or any UIKit views such as UIViewRepresentable. 
 Using such packages would result in an automatic 0 in the respective
 task. You should *not* use **MKMapView()**. Instead, use **Map()**.
-- Might look [here]() for polygons. I have *not* verified this, might cause your laptop to go up in a puff of smoke, work great, or fail to compile.
+- Might look [here](https://medium.com/swlh/how-to-improve-your-swiftui-map-a323ccb47dfb) for polylines via `.addOverlay()`. I have *not* verified this, might cause your laptop to go up in a puff of smoke, work great, or fail to compile. 
 
 ## Video of example app
 [video](assign4.mp4)