KDE-Forum.org

I'm interested in using one or more of the icons from KDE in an open source project being developed by a non-profit organisation. We will be making money selling services for it, but the product itself is distributed for free under the GPL.

Since there is no mention of non-executable binaries (such as artwork) in the GPL, I would assume these images are technically copyright. I can't find any real mention of who did what icons, so could anyone shed some light on who I'd need to contact to get permission to use them?

Thanks.