I have done work at a charity that mails donations of books to prisons called "Books Through Bars", and I am always excited to get a request for books on progra

I have done work at a charity that mails donations of books to prisons called "Books Through Bars", and I am always excited to get a request for books on programming. You may want him to send a request to them, there will be some lag time, but it sounds like he has a bit of time left. I'd go with "Code: The Hidden Language of Computer Hardware and Software" or a Donald Knuth book.