[Lectures on the Hyperreals](http://books.google.ca/books?id=TII-PX_OdloC&printsec=frontcover&dq=Introduction+to+the+Hyperreals&source=bl&ots=Tc8uikixsC&sig=Lkwngtdjp2JaMptWAHG7YMpxi6Q&hl=en&ei=uuWkS__2BsOWtgfS8rS1Dw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CBQQ6AEwAg#v=onepage&q=&f=false) by Goldblatt.