Topology Challenges

Hi guys,

I've been searching online for a specific website which had for download some topology, geometrical challenges in zip format.

I lost the bookmark and I thought it was a great way to learn topology and edge flow.

Basically there would be some images of some polygon geometry shapes which would then have a set of rules - how many vertices and edges you could add to make the topology four-sided...

if anyone knows of such a site pls do reply me...