I remember that several sources provided the entire Wikipedia in ebook formats several years ago before ebook readers became popular. In other words, people still read on PDAs. But I suspect that Wikipedia is now way too large to include the entire site on any reader, unless you could manage to strip out all the images. And even then it would be a huge undertaking. And if you somehow managed to get this into a single book it would be too large for the reader to open without locking up. You would have to divide it into hundreds of books, I think.