Yesterday, when I went to Amazon to buy another one, I was surprised to see this:

This is so foolish for the publisher to limit the availability of electronic books! It took me 1 minute to search and download a copy of the book floating around in the internet after I saw that warning. Indeed, 45 seconds of the one minute were spent cursing the stupid policy.
I was begging to pay them for goods easily found for free and they refused :-(
So, it seems book publishers haven't learned from the music and movie publishers' experiences yet.
As a heavy consumer of books, I would like to suggest that all physical books should include an electronic version for the back up purpose and all pure electronic books should be priced reasonably--they should be priced substantially less than the paperback version. I would be very happy to keep spending money buying books if publishers are reasonable.