The next site I found is www.Free-graphics.com, this site boasts over 30,000 free clip arts and it is easy to search. The sidebar offers a menu list of specific items you can find and use, including animated clipart as well. It offers a sister site called www.iclipart.com, which is membership fee based. Free-graphics.com however, offers quite a good selection within the 30,000 available at no cost. This is both a domain and Attribution. I think this website is credible because the website provides quality images and offers a wide range of pictures and also there is a yearly membership included when signing up.
The last and final website that I found was www.ClipArtOf.com I love the fact that this website not only features free clipart, but also it allows graphic artist the ability to show off their artwork and get recognition for it. The clip art offered is very unique and creative. The categories to choose from are huge and the more an artist contributes the more they are featured on the site. There are also backgrounds available to choose from. This site is a public domain. I found a lot of credibility in this site because there was a lot of recognition for the clipart on the website.