I have a "how to" book that I wrote back in 03 and had it copyrighted. I sell it on my website. I just found out that a "big company" is using it and the pictures as their manual they supply with certain parts. Every copy I sell plainly says that it is copyrighted. I sell them as a cd rom pdf. I have taken every measure to make sure its not reproduced with out my permission. What do I need to do to make sure I am compensated to the fullest extent? And do I have a case?