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2. A. Avron, “The semantics and proof theory of linear logic” (Edinburgh, 1987).
3. G. Birkhoff,Lattice Theory (American Mathematical Society, Prividence, 1966).
4. A. Cantini,Properties and Operations, revised and translated edition ofProprieta' e Operazioni (Bibliopolis, Napoli, 1983), in preparation.
5. G. Cattaneo, C. Garola, and G. Nistico', “Preparation-effect versus question-proposition structures,” to be published inInt. J. Theoret. Phys.