Mahood, H.R.
Pressure groups in American politics
Scribner, 1967
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Eldersveld, Samuel J.
Political parties in American society / Samuel J. Eldersveld
Basic Book inc, 1982
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Michels, Robert, 1876-1936
Political Parties : a sociological study of the oligarchical tendencies of modern democracy
Collier Books, 1962
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Klein, Josephine, 1926-
The study of groups
Routledge and Kegan Paul, 1956
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McKenzie, R.T.
British political parties the distribution of power within the conservative and labour parties
William Heinemann, 1955
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