The legal rights

There are several questions about sample code presented in the newest edition of the Red Book on this forum. The easiest way to help those guys is to build full-working examples. My question is: Do I need some formal approval from the author(s)?

Earlier versions have many authors, but in this one, only Dave Shreiner listed as an author, and I didn’t succeed to find his e-mail or any usable contact-information.

And the second question is: May I modify those examples?

Although it sounds like trivial questions, they are not, and I don’t want to use intellectual property of other people on illegal way. So, please, give me some useful advices.