1. Collected papers of Gerhard Gentzen;gentzen;Studies in logic and the foundations of mathematics North-Holland (English translation),1969
2. The logic of paradox
3. The completeness and compactness of a three-valued first-order logic;d’ottaviano;Revista Colombiana de Matemáticas,1985
4. Gentzen method in modal calculi II;ohnishi;Osaka J Math,1959
5. A Hierarchy of Weak Double Negations