Limited (search only) 1973
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Northwestern University
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Limited (search only) 1984
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Northwestern University
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Limited (search only) 1985
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Northwestern University
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Limited (search only) 1986
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Northwestern University
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Limited (search only) 1988
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Cornell University
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Limited (search only) 1989-91
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Cornell University
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Limited (search only) 1992
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Cornell University
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Limited (search only) 1993
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Cornell University
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Limited (search only) 1994
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Cornell University
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Limited (search only) 1995
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Cornell University
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Limited (search only) yr.1998
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University of California
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