Duverger (1980). „A New Political System Model: Semi-Presidential Government”. European Journal of Political Research (quarterly). 8 (2): 165—187. doi:10.1111/j.1475-6765.1980.tb00569.x. „The concept of a semi-presidential form of government, as used here, is defined only by the content of the constitution. A political regime is considered as semi-presidential if the constitution which established it, combines three elements: (1) the president of the republic is elected by universal suffrage, (2) he possesses quite considerable powers; (3) he has opposite him, however, a prime minister and ministers who possess executive and governmental power and can stay in office only if the parliament does not show its opposition to them.”