Having preached on guidance a few weeks ago (sermon audio can be found here video can be found here I thought it good to recommend a book on the subject.
I read the first edition of this book and back then it was called "The Last Word on Guidance" - when they updated it the publisher didn't think calling it "The Last Word on Guidance II" would work - hence the title "Guidance and the Voice of God". Its an excellent read.

Available direct from the publisher here or on sale here