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By Orr-Love, Michael
By Reiss, Michael J.
By Diana Coben, Elizabeth Atere-Roberts
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By Iddo Gal
By School Mathematics Project
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By John Southcliffe Martineau
By David Blackie
By Collins GCSE
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By Peter V. O'Neil
By Bulent Atalay
By D. W. Ballentyne
By H M. Edwards
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By J. A. L. Matheson, N. W. Murray, R. K. Livesley
By David Baker, etc., Jim Griffith, Paul Hogan, Chris Humble
By William G. Dauben
By William G. Dauben (University of California, Berkeley)
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