Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Hydrophobe:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

where φ is the area fraction of the solid that touches the liquid.[4] Liquid in the Cassie–Baxter state is more mobile than in the Wenzel state.[citation needed]