Leadership theories and styles: A literature review Khan, Z., Irfanullah, A., & Khan, I. (2016). Leadership theories and styles: A literature review. Journal of Resources Development and Management, 16.
The main theories that emerged during the 20th century include the Great Man theory, Trait theory, Process leadership theory, Style and Behavioral theory, Transformational, Transactional and Laissez-Faire leadership theory.