From the Creative Commons FAQ page:
All current CC licenses require that you attribute the original author(s). If the copyright holder has not specified any particular way to attribute them, this does not mean that you do not have to give attribution. It simply means that you will have to give attribution to the best of your ability with the information you do have. Generally speaking, this implies five things:
- If the work itself contains any copyright notices placed there by the copyright holder, you must leave those notices intact, or reproduce them in a way that is reasonable to the medium in which you are re-publishing the work.
- Cite the author’s name, screen name, user identification, etc. If you are publishing on the Internet, it is nice to link that name to the person’s profile page, if such a page exists.
- Cite the work’s title or name, if such a thing exists. If you are publishing on the Internet, it is nice to link the name or title directly to the original work.
- Cite the specific CC license the work is under. If you are publishing on the Internet, it is nice if the license citation links to the license on the CC website.
- If you are making a derivative work or adaptation, in addition to the above, you need to identify that your work is a derivative work i.e., “This is a Finnish translation of the [original work] by [author].” or “Screenplay based on [original work] by [author].”
In the case where a copyright holder does choose to specify the manner of attribution, in addition to the requirement of leaving intact existing copyright notices, they are only able to require certain things. Namely:
- They may require that you attribute the work to a certain name, pseudonym or even an organization of some sort.
- They may require you to associate/provide a certain URL (web address) for the work.
If you are interested to see what an actual license (“legalcode”) has to say about attribution, you can use the CC Attribution 3.0 Unported license as an example. Please note that this is only an example, and you should always read the appropriate section of the specific license in question … usually, but perhaps not always, section 4(b) or 4(c):
The full CC FAQ can be read here.