| Computability Logic: Wikipedia (free encyclopedia) article. |
| 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. |
| 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. |
| Non Standard Logics: A comprehensive listing of flavours of non-standard logic with brief descriptions and references, compiled by Peter Suber. |
| What are Weak Arithmetics: Notes defining the subject. Available in HTML and PS formats. |
Classical
