First of all never lend money and books to anybody. Particularly do not lend it to friends because friends are the real enemies in life as far as money and books are concerned. But if you have made that mistake of lending, then there are two things you can consider doing. First is to write off that debt and forget it. If you cannot do it, then the second method is to pretend to your friend that you have inherited a big fortune through a lottery or gambling or a will from your grandfather. You should then say that you do not know what to do with this huge money. Your friend will naturally approach for a bigger loan. You promise to help him but gently insist that your friend repay the earlier smaller loan he borrowed from you. That does the trick. Within the same day your friend will give back that money with interest. After this, do not lend any further money. Your friendship will also sink, but let it. I followed the above method to recover my money from my dearest friend some years back.