Ronald J. Burke, “Why Leaders Fail: Exploring the Darkside,” International Journal of Manpower 27, no. 1 (2006): 91–100.

Gurdjian, Halbeisen, Lane, “Why Leadership-Development Programs Fail.”

These figures come from Brad Hall, “Today’s Leadership Development Approach Does Not Work,” The Street, 14 апреля 2014 г., www.thestreet.com/story/12668089/1/todays-leadership-development-approach-does-not-work.html