Programming in Prolog: Using the ISO Standard
From the reviews of the fifth edition:"This is the fifth and the most recent edition of a legendary book … . It was probably the first introductory Prolog book and it is still the most gentle introduction to Prolog for everyone, including non-computer scientists. … the book is as great as ever as an introductory text for Prolog. When a newbie asks for an introduction to Prolog, the best advice is still Clocksin & Mellish." (Bart Demoen, TLP-Theory and Practice of Logic Programming, Vol. 5 (3), 2005)