Ralph, P. L. (1997). World civilizations, their history and their culture (9th ed.). W.W. Norton.
芝加哥风格引文Ralph, Philip Lee. World Civilizations, Their History and Their Culture. 9th ed. New York: W.W. Norton, 1997.
MLA引文Ralph, Philip Lee. World Civilizations, Their History and Their Culture. 9th ed. W.W. Norton, 1997.
警告：这些引文格式不一定是100％准确.