What are Weak Arithmetics What are Weak Arithmetics: Notes defining the subject. Available in HTML and PS formats. (Nonstandard Logics and Extensions) http://www.univ-paris12.fr/lacl/jaf/html/wa.html
Computability Logic Computability Logic: Wikipedia (free encyclopedia) article. (Nonstandard Logics and Extensions) http://en.wikipedia.org/wiki/Computability_logic
Infinitary Logic Infinitary Logic: Article in the Stanford Encyclopaedia of Philosophy by John L. Bell. Infinitary Logic is a branch of formal logic where finitary formulae are replaced by potentially infinitary mathematical entities. (Nonstandard Logics and Extensions) http://plato.stanford.edu/entries/logic-infinitary/
Non Standard Logics Non Standard Logics: A comprehensive listing of flavours of non-standard logic with brief descriptions and references, compiled by Peter Suber. (Nonstandard Logics and Extensions) http://www.earlham.edu/~peters/courses/logsys/nonstbib.htm
Logic System Interrelationships Logic System Interrelationships: Shows how a number of representative logics fit together. The interrelationships usually given as something of the form: System X is system Y plus the axiom Z. By John Halleck. (Nonstandard Logics and Extensions) http://www.cc.utah.edu/~nahaj/logic/structures/