Prolog – Wikibooks, open books for an open world

http://en.wikibooks.org/wiki/Programming:Prolog

This book can serve as a textbook or tutorial for anyone who wants to learn the prolog programming language. No prior programming experience is required. Some basic knowledge of logic can come in handy. For those new to the subject, a short introduction to logic is given, but this is not required reading.

Free Online Prolog Tutorials (thefreecountry.com)

http://www.thefreecountry.com/documentation/onlineprolog.shtml

This page lists free online tutorials and references on the Prolog programming language and on logic programming. Many of the tutorials are designed to teach you how to program in Prolog from ground up