Sorry, about that. If the books are not already at the printers then you can created a discount in E-junkie that can be added to the book and the buyer can go to your site, add the two other products to the shopping cart and type in the discount code. If you have the book printed already, or the book file is already at a print on demand publisher, then you would have to manually setup or send the buyers the download link once they provide proof that they purchased your printed book.