What does each underlined part refer to?

Some states do not recognize a right for people to will publicity rights to their heirs, whether or not the celebrities exploit the rights commercially during their lifetime. In these states, rights of publicity die with the person. They tend to emphasize the personal nature of the right of publicity and the difficulties in treating (a)such rights as independent of the people who made (b)them valuable.

What are the referents of (a) and (b)? Could you pinpoint them in the text?

Thank you so much.