Sites

E.L. Post Manuscript Guide (Popularity: )
http://www.amphilsoc.org/library/mole/p/post.htm
Notes on papers and correspondence by Post at the American Philosophical Society.

Emil Post (Popularity: )
http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Post.html
Biography of Emil Leon Post (1897-1954).

Aristotle's Logic (Popularity: )
http://www.philosophypages.com/hy/2n.htm
Introductory article by Garth Kemerling.

Peter of Spain (Petrus Hispanus) (Popularity: )
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.

On Sense and Reference (Popularity: )
http://wikisource.org/wiki/On_Sense_and_Reference
English translation of Gottlob Frege's 1892 "Über Sinn und Bedeutung," by Max Black.

Square of Opposition (Popularity: )
http://plato.stanford.edu/entries/square/
Article in the Stanford Encyclopaedia of Philosophy, by Terence Parsons.

Kenny's Overview of Hofstadter's Explanation of Gödel's Theorem (Popularity: )
http://www.ncsu.edu/felder-public/kenny/papers/godel.html
A reasonably detailed explanation of Godel's Theorem by Kenny Felder.

The Summulae of John Buridan (Popularity: )
http://www.fordham.edu/gsas/phil/klima/Intro.htm
A critical introduction by Gyula Klima.

Mediaeval Logic and Philosophy (Popularity: )
http://pvspade.com/Logic/
Resource maintained by Paul Vincent Spade at Indiana University.

Alan M. Turing (Popularity: )
http://plato.stanford.edu/entries/turing/
Entry from the Stanford Encyclopedia of Philosophy by Andrew Hodges.

Scholastic Logic (Popularity: )
http://www.nd.edu/Departments/Maritain/etext/perrier2.html
Chapter Two of Joseph Perrier's "The Revival of Scholastic Philosophy in the Nineteenth Century" (1909).

Scholasticism (Popularity: )
http://www.nd.edu/Departments/Maritain/etext/scholas1.htm
Online text by Joseph Rickaby (1908).

Logic (Popularity: )
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.

Hilbert's Problems (Popularity: )
http://www.mathacademy.com/pr/prime/articles/hilbert_prob/
Article in the Platonic Realms. Lists 23 problems posed to the second international mathematics congress in 1900 AD.

Medieval Theories of Modality (Popularity: )
http://plato.stanford.edu/entries/modality-medieval/
Article at the Stanford Encyclopaedia of Philosophy.

Aristotle's Reform of Paideia (Popularity: )
http://www.bu.edu/wcp/Papers/Anci/AnciBark.htm
Article by Evelyn Barker, arguing that the principal aim of Aristotle's Organon was to reform the contemporary paedagogical role of dialectic.

Alan Turing Papers (Popularity: )
http://janus.lib.cam.ac.uk/db/node.xsp?id=EAD%2FGBR%2F0272%2FAMT
Collection record of Turings papers at Kings College, Cambridge.

Alan Turing (Popularity: )
http://www.wikipedia.org/wiki/Alan_Turing
Encyclopedia biography from Wikipedia.

Alan Turing: The Biography Project (Popularity: )
http://www.popsubculture.com/pop/bio_project/alan_turing.html
Biography, bibliography and links.

Aristotelian and Modern Logic (Popularity: )
http://www.ifs.csic.es/sorites/Issue_04/item5.htm
Article by Katalin Havas, discussing the nature of progress in logic, and the idea of logic as a perfected discipline.