Biebel, David B. Your mind at its best : 40 ways to keep your brain sharp / David B. Biebel, James E. Dill, Bobbie Dill. - Grand Rapids, Mich. : Revell, 2011. - 233 pages. Includes bibliographical references (p. 217-233). ISBN: 9780800732929 LCCN: 2010027863 Subjects--Topical Terms: Mental health. LC Class. No.: RA790.53 / .B44 2011 Dewey Class. No.: 613