Library of Congress Subject Headings is an alternative to keyword searching. They can narrow down your search much more effectively than keywords.
Here are some good subject headings to use in your searches on Comparative Politics
Encyclopedia of Political Thought
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International Encyclopedia of Political Science
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The Oxford Companion to Politics of the World
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Encyclopedia of Crime and Justice
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Encyclopedia of Criminology
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A New Handbook of Political Science
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The Oxford Handbook of Political Theory
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21st Century Political Science
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The Oxford Handbook of Criminology
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21st century criminology a reference handbook
The Blackwell Dictionary of Political Science
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The Facts on File Dictionary of American Politics
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The Palgrave Macmillan Dictionary of Political Thought
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The Routledge Dictionary of Politics
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