Attorney and professional photographer Carolyn E. Wright has a blog called Photo Attorney®. While some of her posts relate specifically to photographers, many apply equally to authors.
Excerpts from a post about what you should/might do if you discover someone is infringing your copyright:
You’re sitting in your easy chair and surfing the web. You’re not paying much attention, until you see it. It’s your photo, but you did not post it there. You can’t believe they used your photo without your permission. Now what do you do? The steps you take may limit your ultimate remedies so be sure to first understand what your options are.
Make Copies of the Infringement
If you think that the use is likely an infringement, make copies of it – both in electronic and print forms. Once the infringer realizes that she is caught, she will do what she can to get rid of the evidence of the infringement. You may need that evidence later.
If the infringement is in print, then take a photograph of it, scan it, photocopy it, and/or show it to another person who would be willing to testify about it. If the infringement is on the Internet and/or in electronic form, make a paper print of it and/or copy a screen capture of it; both are better!
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Research the Infringer
Next, find out what you can about the infringer. Research the infringer’s website to find his name and contact information. If the infringer is a corporation based in the United States, you can find information about it on the website of the Secretary of State for the state where the infringer is based. To find the Secretary of State’s website using an Internet search engine such as Google, search the corporation’s state’s name (such as “Georgia”) and the words “secretary of state.” The extension of the URL will be “.gov” or “.us.” Be careful – some sites attempt to appear to be the state’s website so that they can charge you for the information. Once on the proper Secretary of State’s website, look for “corporations search,” “business search” or similar language. You then will find the company’s registered or resident agent, officers, and/or official address.
You also may be able to find a contact name by searching the website’s “who is” information.
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Option #1 – Do Nothing
Now that you’ve documented the infringement and have some information about the infringer, you always have the option of doing nothing. If the infringer is in a foreign country where infringements are rampant and difficult to enforce or is a small website with little traffic, you may decide that it’s not worth your time and effort to fight the infringement.
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Option #4 – Prepare a Cease and Desist/Demand Letter Yourself
When you don’t want to alienate the infringer (the infringer is a potential client and/or appears to be an innocent infringer), you may want to contact the infringer to explain that the use is not authorized and either request payment of an appropriate license fee, a photo credit with a link to your website (as discussed above), or that the infringer cease use of the image. It’s best to do this in writing – a letter by surface mail seems to have more clout than email correspondence.
Link to the rest at Photo Attorney® There are lots of useful copyright posts plus Carolyn also has some great photos on her site.