Okay, I'm not that picky, but here are the rules and they must be followed!
1. You must mention us in all of your art using our stock and give a link to our stock site.
2. Send us a comment or note of what you have done so we can look at it!
3. You must not(this means not allowed EVER) use our stock for any pornography or racial/hate art.
4. You must ask before making prints using our stock, but you can use it outside of DeviantArt. We don't bite, just ask!
5.You must make an effort with our stock. No changing colors or just adding a new background*, fixing mistakes in the picture, that sort of thing. You are not allowed to post it to your site as your artwork if you have done so. You guys can do it, we have no doubt!
*this does not include stock that is used as a background, such as our japanese garden photos. In that case, you must do something to the foreground.
P.S. We love to see our stock used as a reference for traditional art as well, so feel free to do so and tell us!