Revolutionary Mafiosi: Voice and Exit in the 1890s, by John Alcorn, in: Paolo Viola & Titti Morello (eds.), L'associazionismo a Corleone: Un'inchiesta storica e sociologica (Istituto Gramsci Siciliano, Palermo, 2004)
Biography of Vito Cascio Ferro on The American Mafia (Sources: "Petrosino Slayer may be in custody" 7 April 1909; "Told a story of Petrosino murder" 29 December 1912; "The origin of organized crime" by David Critchley; "The history of the Sicilian Mafia" by John Dickie)