[1] Ohama Shigeo:
On a formalism which makes any sequence of symbols well-formed. Nagoya Math. J. 32 (1968), 1-4.
MR 0231705
[2] Church Alonzo:
An introduction to Mathematical Logic, Part I. Princeton University Press, Princeton 1956.
MR 1435972
[3] Gentzen Gerhardt: Untersuchungen über das Logische Schliessen. Mathem. Zeitschrift 39 (1934-5), 176-210, 405-431.
[4] Kramosil Ivan:
Statistical Estimation of Deducibility in Polyadic Algebras. Kybernetika 7 (1971), 3, 181-200.
MR 0300881