Inside a library book, I found a printed-out email from one author of the book to the other, about the book. The book was Programming in Prolog by Clocksin and

Inside a library book, I found a printed-out email from one author of the book to the other, about the book. The book was Programming in Prolog by Clocksin and Mellish, in the library of the University where Mellish was based at the time of the email. The email is dated 1988; I found it about twenty years later! The piece of paper also has the name of another academic handwritted on the other side.