Key, V. O. (1960). Politics, parties, and pressure groups (4th ed.). New York: Thomas Y. Crowell Company.
Παραπομπή Chicago StyleKey, V. O. Politics, Parties, and Pressure Groups. 4th ed. New York: Thomas Y. Crowell Company, 1960.
Παραπομπή MLAKey, V. O. Politics, Parties, and Pressure Groups. 4th ed. New York: Thomas Y. Crowell Company, 1960.
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