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Peter of Spain (Petrus Hispanus) - http://plato.stanford.edu/entries/peter-spain/
Life and work of 13th century logician and author of the Tractatus; from the Stanford Encyclopedia by Joke Spruyt. |
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http://www.newadvent.org/cathen/09324a.htm - http://www.newadvent.org/cathen/09324a.htm
Entry in the Catholic Encyclopaedia (1917), dominated by a historical survey from Indian and Pre-Aristotelian philosophy to the Logic of John Stuart Mill. |
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Aristotle's Logic - http://www.philosophypages.com/hy/2n.htm
Introductory article by Garth Kemerling. |
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Syllogistic logic online - http://aristotelianlogic.glashoff.net
This site contains an online program for studying Aristotle's syllogistic logic. The theory of Aristotle's ancient logic is also presented. |
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The Summulae of John Buridan - http://www.fordham.edu/gsas/phil/klima/Intro.htm
A critical introduction by Gyula Klima. |