Gavin,
I’m always on the lookout for a good drawing book, and places like Borders / B & N etc. have loads of painting but few drawing books. I happened by a bookstore on my old walking route to the metro a few years back ~ I can’t remember the name of it ~ Bader and Bader? ~ but it was a small specialty shop and they had several good books of Drawings. I also look for Drawing books at museums, but even there, there aren’t usually very many.
I’m not sure that the link is right ~ but the author / editor is Salvatore Nigro. It seems to be part of a series of books, IL LIBRO MIO. I’ll let you know if I find a link anywhere ~ I looked for one on Amazon, and the link I posted was as close as I could find.
I can’t recall how much this book was, but it was somewhere around $80~$100. Me likes. Me likes a lot! 
Cheers, 
~Rebeccak