1. Entailment 1;Anderson,1975
2. The weak theory of implications;Church,1951
3. Meyer 1966 - Topics in Modal and many valued logics Thesis 1966
4. The deduction theorems and two new logical systems;Moh;Methods,1950
5. M., Wajsberg, 1931 - Axiomatization of the three valued propositional calculus (in Polish). comptes rendus des seances de la Societe des Sciences et des Lettres de varsovie, classe III, vol. 24, pp. 126–148.