Here’s an email I just sent Fred Shapiro, editor of the Yale Book of Quotations:
I don’t see a web version on the website. There should be one. Your publisher may be worried about losing book sales. What you can do is this:
1. Put a serial number in each book.
2. The buyer sends in his serial number an email address.
3. He then gets a password.
4. A new password is emailed to that serial number every year (or month, or whatever), replacing the old one.
That would be good enough security to avoid most cannibalization, I think, and would greatly increase the value of the book.
Publishers *should* know about simple things like this, but I bet they don’t, and think security requires something more burdensome for all concerned.