Pei, M. (1970). Words in sheep's clothing. Allen and Unwin.
Cita Chicago (17th ed.)Pei, Mario. Words in Sheep's Clothing. London: Allen and Unwin, 1970.
Cita MLA (8th ed.)Pei, Mario. Words in Sheep's Clothing. Allen and Unwin, 1970.
Atenció: Aquestes cites poden no estar 100% correctes.