Willingham, R. (1997). The people principle: A revolutionary redefinition of leadership. St. Martins press.
Chicago-čujuhus (17. p.)Willingham, Ron. The People Principle: A Revolutionary Redefinition of Leadership. New York: St. Martins press, 1997.
MLA-čujuhus (9. p.)Willingham, Ron. The People Principle: A Revolutionary Redefinition of Leadership. St. Martins press, 1997.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.