I'm just curious... how come some of your books are available on pdf, but others aren't? I'd love to buy more pdf's, even of books that I already have print copies of.

All the Sudoku Xtra books and magazines are available as PDFs. However while the PDFs of the magazines, and printed versions of the books, are both popular, there is no overlap. That is, no one buys the PDFs of the single puzzle books, and most people choose the PDF of the magazine. So now I don't bother with PDF versions of non-Sudoku Xtra books because they won't sell so it's not worth the time spent preparing them.

Thanks, Gareth. I'm asking because I would much rather have the books on pdf. Books take up so much room, and they're heavy to move when you have a lot of them I bought the pdf verion of Consecutive Sudoku Volume 1 from Amazon, and when I noticed that the pdf was available here, I bought that, too (Great book, btw. I'm working on your 200 Consecutive now and loving it).