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2. [Blizard 1989] Blizard, W. D. 1989. Multiset theory, Notre Dame Journal of Formal Logic, 30, 36-66.
3. [Blizard 1990] Blizard, W. D. 1990. Negative Membership, Notre Dame Journal of Formal Logic, 31, 346-368.
4. [Blizard 1991] Blizard, W. D. 1991. The Development of Multiset Theory, Modern Logic, 1, 319-352.
5. [Boole 1854] Boole, G. 1854. An Investigation of the Laws of Thought, Cambridge: MacMillan; London: Walton and Maberly. [Several reprs.]