Apinyan, Levon A., and Anahit A. Chubaryan. “On Sizes of Linear and Tree-Like Proofs for Any Formulae Families in Some Systems of Propositional Calculus”. Mathematical Problems of Computer Science 57 (June 1, 2022): 47–55. Accessed July 26, 2024. http://mpcs.sci.am/index.php/mpcs/article/view/734.