Franchetti 1877, pp. 163–164: (Italian) "Laonde il sostantivo mafia ha trovata pronta una classe di violenti e di facinorosi che non aspettava altro che un sostantivo che l'indicasse, ed alla quale i suoi caratteri e la sua importanza speciale nella società siciliana davano diritto ad un nome diverso da quello dei volgari malfattori di altri paesi." Franchetti, Leopoldo (1877). Condizioni Politiche e Amministrative della Sicilia. Firenze: G. Barbera.
Gambetta 2009: "The mafia's principal activities are settling disputes among other criminals, protecting them against each other's cheating, and organizing and overseeing illicit agreements, often involving many agents, such as illicit cartel agreements in otherwise legal industries. Mafia-like groups offer a solution of sorts to the trust problem by playing the role of a government for the underworld and supplying protection to people involved in illegal markets ordeals. They may play that role poorly, sometimes veering toward extortion rather than genuine protection, but they do play it." Gambetta, Diego (2009). Codes of the Underworld. Princeton University Press. ISBN978-0691119373.
Pike, John (3 October 1998). "La Cosa Nostra". Federation of American Scientists Intelligence Resource Program. Archived from the original on 27 January 2022.
Dimico, Arcangelo; Olsson, Ola; Isopi, Alessia (2012-05-13). "Origins of the Sicilian Mafia". VoxEU.org. Archived from the original on 2017-04-12. Retrieved 2017-04-12.
web.archive.org
Pike, John (3 October 1998). "La Cosa Nostra". Federation of American Scientists Intelligence Resource Program. Archived from the original on 27 January 2022.
"Sicily And The Mafia". americanmafia.com. February 2004. Archived from the original on 2017-09-22. Retrieved 2019-04-08.
Dimico, Arcangelo; Olsson, Ola; Isopi, Alessia (2012-05-13). "Origins of the Sicilian Mafia". VoxEU.org. Archived from the original on 2017-04-12. Retrieved 2017-04-12.