Cita APA

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

Citación estilo Chicago

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

Cita MLA

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