Google Search for WP websites only

Hi there!

I had no idea where to post this thread, so be patient with me if this is the wrong section.

Is there any way you may know to do a search on google and filter the results to WordPress websites only?
Something like a special search or any way to search by reading the HTML code?

I hope you'll be able to help me, and I hope this can be useful to others as well.
Meanwhile, I'll work on it and try to find a solution.

Cheers.