Explore Leadership Sources:Leadership LeadershipThis category has 3 sources. McKee A, Boyatzis RE, Johnston F. 2008. Becoming a resonant leader: develop your emotional intelligence, renew your relationships, sustain your effectiveness. :231. Kegan R. 1994. In over our heads: the mental demands of modern life. Intrator SM, Scribner M. 2007. Leading from within: poetry that sustains the courage to lead. :252.