"Background to the Italian Renaissance", Washington State University "The Rise of the Italian City-States" "Italy's City-States", End of Europe's Middle Ages, University of Calgary "City-states in Italy", Web Gallery of Art
«Background to the Italian Renaissance», Университет штата Вашингтон «The Rise of the Italian City-States» «Italy’s City-States», End of Europe’s Middle Ages, Университет Калгари «City-states in Italy», Web Gallery of Art