Balsamiq does not claim intellectual property rights over wireframes created with Balsamiq Mockups or myBalsamiq (more info).
That said, if you use images created with Balsamiq Mockups or some of our icons in a book, eBook, website, software, or advertisement, we'd appreciate a little mention, something small like this
Created with Balsamiq Mockups.
Here's the HTML for it:
<em><small> Created with <a href="https://balsamiq.com/products/mockups">Balsamiq Mockups</a>.</small></em>
Peldi's wife Mariah and our nice guy designer Mike have put a lot of love into creating those wireframe pieces, they deserve a little credit don't you think?