That first one there, Fun With a Pencil, I can't recommend highly enough. It's the most comprehensive explanation of drawing by volume I've ever seen, perhaps because it was explaining things which really hadn't yet been explained before - I think later art instruction books took for granted the fact that you can find this information elsewhere.
If you have even the slightest interest in being able to draw, grab a pad of paper and run through the excercises. Your skill will improve, as will your confidence as the guesswork disappears.
The other book, I'm less excited about. But, it's got lots of pretty illustrations to admire.
Anyway, go. Read. Download the PDF versions in case the site disappears.