2000 - Imperfect Balance (Hardcover) → Paperback ISBN-13: 9780231111560 ISBN-10: 0231111568 Genres: Nonfiction, Science & Math, Engineering & Transportation ? 2000 - Imperfect Balance (Paperback) → Hardcover ISBN-13: 9780231111577 ISBN-10: 0231111576 Genres: History, Nonfiction, Science & Math ? |