Political Parties: A Sociological Study of the Oligarchical Tendencies of Modern Democracy is a book by sociologist
Robert Michels, published in 1911 and first introducing the concept of
iron law of oligarchy. It is considered one of the classics of
social sciences, in particular sociology and
political science. It was translated to Italian as
Sociologia del partito politico nella democrazia moderna: studi sulle tendenze oligarchiche degli aggregati politici by Alfredo Polledro in 1912, and then translated from the Italian to English by
Eden Paul and
Cedar Paul for Hearst's International Library Co. in 1915.