e-book formatting

By the way, a comment about TidBITS' e-books. They are easy to read. Not only in the way of language, but also typographically.
It is difficult to format PDF pages well for both paper and screen reading. And most don't do it well. Adobe, inventor of PDF, is one of the worst offenders: their PDF documents usually have such tiny type and such long lines that I have to all but give up reading them, printed or not. But TidBITS have found a good way, I think: the text is so large that you can easily read it, even showing a full page on screen. (At least on a largish monitor.) And if you want to print it out, you can easily avoid too much paper waste by formatting it with two pages of book per one page of paper. It's a good idea.