1. K.Ajdukiewicz, ‘Die syntaktische Konnexität’, Studia Philosophica 1 (1935) 1–27; translated as ‘Syntactic Connexion’ in Polish Logic (ed. by S. McCall), Oxford, 1967, pp. 635–647. (Page references are to the translation.)
2. A.Church, ‘A Formulation of the Simple Theory of Types’, Journal of Symbolic Logic 5 (1940) 56–68.
3. M.J.Cresswell, Logics and Languages, Methuen, London, 1973.
4. L.Goddard and R.Routley, The Logic of Significance and Context, volume 1, Scottish Academic Press, Edinburgh, 1973.
5. L.Henkin, ‘Completeness in the Theory of Types’, Journal of Symbolic Logic 15 (1950) 81–91; reprinted in The Philosophy of Mathematics (ed. by J. Hintikka), Oxford, 1969, pp. 51–63.