^Schmid, Alex P. (2013). “Radicalisation, De-Radicalisation, Counter-Radicalisation: A Conceptual Discussion and Literature Review”. Terrorism and Counter-Terrorism Studies (The International Centre for Counter-Terrorism) 4 (2). doi:10.19165/2013.1.02.
^"Types of social movements". Encyclopædia Britannica. 2020年1月10日閲覧。Social movements may also be categorized on the basis of the general character of their strategy and tactics; for instance, whether they are legitimate or underground. The popular distinction between radical and moderate movements reflects this sort of categorization.
Calhoon, Robert McCluer (2008), Ideology and social psychology: extremism, moderation, and contradiction, Cambridge University Press, ISBN978-0-521-73416-5