Angell - Note on a Less Restricted Type of Rule of Inference
May - Wittgenstein Reflection on Lewis Carroll Looking Glass
Carroll - Symbolic Logic
Boghossian - Epistemic Rules
Wittgenstein - Notes on Logic.pdf
Abeles - Toward a Visual Proof System - Lewis Carroll Method of Trees
Anderson - Wittgenstein and Nagarjuna's Paradox
Nadejda - Independence of the Axioms and Rules of Inference of One System of the Extended Propositional Calculus
Buchalter - The Logic of Nonsense