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2. On formal properties of simple phrase structure grammars;Bar-Hillel;Zeitschrift für Phonetik, Sprachwissenschaft, und Kommunikationsforschung,1961
3. Winning Ways for your mathematical plays;Berlekamp,1982
4. Axiomatische Untersuchung des Aussagen-Kalkuls der “PrincipiaMathematica”;Bernays;Mathematische Zeitschrift,1926
5. Playing with Boolean Blocks, Part I: Post’s lattice with applications to complexity theory;Böhler;ACM SIGACT News,2003