1. L. Åqvist, ‘Reflections on the Logic of Nonsense’, Theoria
28 (1962) 138–57.
2. N. D. Belnap, Jr., ‘Intensional Models for First-Degree Formulas’, Journal of Symbolic Logic
32 (1967) 1–22.
3. G. Birkhoff, Lattice Theory, 3rd ed., Providence, R.I., 1967.
4. D. Bochvar ‘Ob odnom trechznachnom ischislenii i evo primenenii k analyzu paradoksov klassicheskovo rashirennovo funktionalnovo ischislenii’, Matemati- cheskij Sbornik
46 (n.s. 4) (1938) 287–308. See also review in Journal of Symbolic Logic 4 (1939) 98, and correction, ibid. 5 (1940) 119.
5. A. Church, Introduction to Mathematical Logic, Vol. I, Princeton, N.J., 1956.