1. Pillay A., “Countable models of stable theories,” Proc. Amer. Math. Soc., 89, No. 4, 666–672 (1983).
2. Sudoplatov S. V., “On powerful types in small theories,” Siberian Math. J., 31, No. 4, 118–128 (1990).
3. Sudoplatov S. V., “Type reduction and powerful types,” Siberian Math. J., 33, No. 1, 150–159 (1992).
4. Goncharov S. S. and Ershov Yu. L., Constructive Models, Consultants Bureau, New York, NY (2000).
5. Handbook of Mathematical Logic. Vol. 1: Model Theory, North-Holland, Amsterdam etc. (1982).