1. Barwise J. Admissible sets and structures, B., Springer-Verlag, 1975.
2. Ershov Yu.L. The principle of Σ-enumeration, Doklady AN SSSR, 1983, v.270, No 5, p. 786–788.
3. Ershov Yu.L. The dynamic logic over admissible sets, Doklady AN SSSR, 1983, v.273, No 5, p. 1045–1048.
4. Goncharov S.S., Sviridenko D.I. Σ-programming. In: Vychislitel'nye sistemy, vyp.107, Novosibirsk, 1985.