Best Drupal Book for Content Managers

Hello - I've seen a number of book reviews in various Drupal groups... most (if not all) focus on applicability for developers. Are there any books that would be most ideal for content managers of pre-existing Drupal sites? Basic how-to, navigation, terminology, etc? A supplemental training aid for those non-technical folks who manage the day-to-day content management.

Thanks for your input.