Analysis of information sources in references of the Wikipedia article "All rights reversed" in Indonesian language version.
It is a legal mistake to use a backwards C in a circle instead of a copyright symbol. Copyleft is based legally on copyright, so the work should have a copyright notice. A copyright notice requires either the copyright symbol (a C in a circle) or the word "Copyright". A backwards C in a circle has no special legal significance, so it doesn't make a copyright notice. It may be amusing in book covers, posters, and such, but be careful how you represent it in a web page!
