diff --git a/README.md b/README.md
index cb757b6..bb5e185 100644
--- a/README.md
+++ b/README.md
@@ -6,9 +6,9 @@ In the domain of information visualization, physical simulations are useful for
 
 [<img alt="Force-Directed Graph" src="https://raw.githubusercontent.com/d3/d3-force/master/img/graph.png" width="420" height="219">](https://observablehq.com/@d3/force-directed-graph)[<img alt="Force-Directed Tree" src="https://raw.githubusercontent.com/d3/d3-force/master/img/tree.png" width="420" height="219">](https://observablehq.com/@d3/force-directed-tree)
 
-You can also simulate circles (disks) with collision, such as for [bubble charts](http://www.nytimes.com/interactive/2012/09/06/us/politics/convention-word-counts.html) or [beeswarm plots](https://observablehq.com/@d3/beeswarm):
+You can also simulate circles (disks) with collision, such as for [bubble charts](http://www.nytimes.com/interactive/2012/09/06/us/politics/convention-word-counts.html) or [beeswarm plots](https://bl.ocks.org/mbostock/6526445e2b44303eebf21da3b6627320):
 
-[<img alt="Collision Detection" src="https://raw.githubusercontent.com/d3/d3-force/master/img/collide.png" width="420" height="219">](https://observablehq.com/@d3/collision-detection)[<img alt="Beeswarm" src="https://raw.githubusercontent.com/d3/d3-force/master/img/beeswarm.png" width="420" height="219">](https://observablehq.com/@d3/beeswarm)
+[<img alt="Collision Detection" src="https://raw.githubusercontent.com/d3/d3-force/master/img/collide.png" width="420" height="219">](https://observablehq.com/@d3/collision-detection)[<img alt="Beeswarm" src="https://raw.githubusercontent.com/d3/d3-force/master/img/beeswarm.png" width="420" height="219">](https://bl.ocks.org/mbostock/6526445e2b44303eebf21da3b6627320)
 
 You can even use it as a rudimentary physics engine, say to simulate cloth: