Wilfried Sieg, Saverio Cittadini. Normal Natural Deduction Proofs (in Non-classical Logics). In Dieter Hutter, Werner Stephan, editors, Mechanizing Mathematical Reasoning, Essays in Honor of Jörg H. Siekmann on the Occasion of His 60th Birthday. Volume 2605 of Lecture Notes in Computer Science, pages 169-191, Springer, 2005. [doi]
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