Roche, J. P., & Levy, L. W. (1964). Parties and pressure groups. Harcourt, Brace & World.
Lua i Stíl Chicago (17ú heag.)Roche, John Pearson, agus Leonard Williams Levy. Parties and Pressure Groups. New York: Harcourt, Brace & World, 1964.
Lua MLA (9ú heag.)Roche, John Pearson, agus Leonard Williams Levy. Parties and Pressure Groups. Harcourt, Brace & World, 1964.
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