Improve Excel skils

Any recommandation on what kind of books/reference that can improve/enhance Excel skill for use in accouts job. or any courses that can jpoin to learn mroe skills on use of Excel. ThanksI would like to recommand The Exam Crams, which are by far the best studying companions. Since discovering the study guides, I have been able to cut my study time and simplified the whole learning process. They are indispensable for those in self-study programs. I owe a great deal to the Exam Cram series.