World Quotes - Page 637
Mihaly Csikszentmihalyi (2004). “Good Business: Leadership, Flow, and the Making of Meaning”, p.30, Penguin
Michel de Montaigne, John Michael Cohen (1959). “Essays”, Penguin Classics
Michael Mandelbaum (2010). “The Frugal Superpower: America's Global Leadership in a Cash-Strapped Era”, p.194, PublicAffairs