International Political Science Association & Ehrmann, H. W. (1958). Interest groups on four continents: Ed. for the International Political Science Association. Pittsburgh U.P..

International Political Science Association and Henry W. Ehrmann. Interest Groups on Four Continents: Ed. for the International Political Science Association. Pittsburgh: Pittsburgh U.P., 1958.

International Political Science Association and Henry W. Ehrmann. Interest Groups on Four Continents: Ed. for the International Political Science Association. Pittsburgh U.P., 1958.