Mafia
2 of the 7 encyclopedias on this shelf carry an entry for Mafia. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
ma-fe'a, a secret society of Italy. It originated in Sicily toward the close of the nineteenth century. The members avenge their wrongs, real or fancied, with the stiletto. They are bound by oath not to carry any dispute into court and not to give evidence if summoned as witnesses. If anyone offend the Mafia, members are detailed by the officers of the organization to take the offender's life. Locally the society is noted for assassinations, and for an undue influence in the control of elections and other public matters. Owing to the large Italian emigration to the United States in the last quarter of the century, the Mafia has made its appearance in New Orleans , Chicago, New York , and other large cities. No Italian dare on his life give the police authorities information relative to the workings of the society. In Sicily the Mafia rose to such a pitch that it became a national scandal. Extortion, blackmail, theft, arson, and the silent stiletto made life hardly endurable. The police shared the profits; the soldiers protected the police; the very judges on the bench protected the criminals and saw to it that none were convicted. Finally, King Victor Emmanuel took action. He sent some honest regiments from the Tyrol and the border of Switzerland to the scene. They swept the island. Unless a man could clear his skirts of suspicion he was shot. Over 5,000 members of the Mafia, and like enough some innocent persons, were executed on the spot. So far as organization goes, the Mafia was crushed. Many migrated to America. So far as America is concerned, the worst outbreak occurred in New Orleans among the Italians engaged in loading and unloading ships. There were two rival organizations of stevedores. The stiletto societies began to get in their work. David Hennessy, chief of police, was stabbed in the back on the night of October 16, 1890. He had just passed a dark doorway in which the assassins were lurking. The citizens rose and lynched a lot of the worst characters they could lay hands on. What is left of the Mafia exists, it is believed, in local stiletto clubs without a widespread organization, and yet every now and then murders are committed thousands of miles apart that suggest the existence of some criminal directing central agency. See Sicily
Collier's New Encyclopedia (1921)
THE, a Sicilian secret society akin to the CAMORRA (q. ข.) in Naples. The Mafia, under one designation or another, runs back to the Middle Ages. It punished crimes against itself by death. Under the Bourbons its simplest form was brigandage and sequestration of the person, to be held to ransom, default of which implied death. When Sicily was annexed to Italy outlawry was increased by the addition of the partisans of the Bourbons, who pretended to be in insurrection. The disorders were suppressed by the bersaglieri, who scoured the country and tried by drum-head court-martial all the men they caught with arms, or who were accused of brigandage, and shot the condemned on the spot. After the re-establishment of civil rule in the island there was a revival of the Mafia. Minor crimes are still somewhat protected by the organization, but the policy of the government has been one of steady legal pressure and change of venue to the Continent for the trial of the criminals, and this is gradually paralyzing the Mafia. This policy resulted in the emigration of large ge numbers of the Mafiosi to the Southern States of the United States. In New Orleans an attempt to stamp out the organization resulted in 1890 in complications between Italy and the United States. The Italian government in recent years has succeeded partially in controlling the Mafia, and its influence in the United States has ceased to become important.