1. Yu. I. Merzlyakov, "On the theory of generalized solvable and generalized nilpotent groups," Algebra Logika,2, No. 5, 29–36 (1963).
2. P. Hall, "A note on SI-groups," J. London Math. Soc.,39, No. 2, 338–344 (1964).
3. G. A. Noskov, "Subnormal structure of Merzlyakov's congruence group," Sib. Mat. Zh.,14, No. 3, 680–683 (1973).
4. Lecture Notes in Math.;J. S. Wilson,1974
5. M. I. Kargapolov and Yu. I. Merzlyakov, Fundamentals of the Theory of Groups [in Russian] 3rd edn., Nauka, Moscow (1982).