Citazione Stile APA (7a Edizione)

Ralph, P. L. (1997). World civilizations: Their history and their culture (9. ed.). Norton.

Citazione stile Chigago Style (17a edizione)

Ralph, Philip Lee. World Civilizations: Their History and Their Culture. 9. ed. New York: Norton, 1997.

Citatione MLA (9a ed.)

Ralph, Philip Lee. World Civilizations: Their History and Their Culture. 9. ed. Norton, 1997.