(Miller, W. R., Rollnick, S. (2002). Motivational Interviewing: Preparing People for Change. 2nd Ed, The Guildford Press, London.)
Despite there being numerous books on motivational interviewing and plenty of updated textbooks, this one is a great start for gaining a deeper understanding of change rather than just being able to identify the phase in which a person may be. The structure males learning the main concepts quite simple and there’s a good range of case studies meaning you should be ale to find an example that the reader can relate to.