Knightley, P. (1987). The second oldest profession: Spies and spying in the twentieth century (1st American ed.). Norton.
Cita Chicago Style (17a ed.)Knightley, Phillip. The Second Oldest Profession: Spies and Spying in the Twentieth Century. 1st American ed. New York: Norton, 1987.
Cita MLA (9a ed.)Knightley, Phillip. The Second Oldest Profession: Spies and Spying in the Twentieth Century. 1st American ed. Norton, 1987.
Precaución: Estas citas no son 100% exactas.