@vrt: Since non of this is profittable, I think you are baing too hard with the formality about the art credits. He said and linked where he took the art from in the beginning of his submission, it's not neccesary to repeat it under every single image.
We all respect the artists we have, so we do with the sites we use as sources. If there is a place where the source must be cited and it isn't, there is always a card curator, admin, you or anyone that notices it and it is corrected as soon it's seen.
Just don't be too exquisite when the source is atually cited (and doesn't say "google")