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[2] C¸ uvalcı˘glu G., Heyting Valued Omega Free Algebra, C¸ ukurova University Institute of Science and Technology, PhD Thesis, Adana, 2002, 68 p.
[3] Faith C., Algebra: Rings, Modules and Categories I, Springer-Verlag, Berlin
[4] Heyting, A. “Die formalen Regeln der intuitionistischen Logik,” in three parts, Sitzungsberichte der preussischen Akademie der Wissenschaften: 42–71, 158–169,1930. English translation of Part I in Mancosu 1998: 311–327.
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