Roche, J. P., & Levy, L. W. (1964). Parties and pressure groups. Harcourt, Brace & World.
Dyfyniad Arddull ChicagoRoche, John Pearson, and Leonard Williams Levy. Parties and Pressure Groups. New York: Harcourt, Brace & World, 1964.
Dyfyniad MLARoche, John Pearson, and Leonard Williams Levy. Parties and Pressure Groups. Harcourt, Brace & World, 1964.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.