[1] F. W. Anderson, K. R. Fuller: Rings and categories of modules. Springer-Verlag, New York-Heidelberg-Berlin, 1974. MR 0417223 | Zbl 0301.16001

[2] L. Bican T. Kepka, P. Němec: Rings, modules, and preradicals. M. Dekker Inc., New York - Basel, 1982. MR 0655412

[3] K. R. Goodearl: Von Neumann regular rings. Pitman, London-San Francisco-Melbourne, 1979. MR 0533669 | Zbl 0411.16007

[4] S. Shelah: Whitehead groups may be not free, even assuming CH, I. Israel. J. Math. 28 (1977), 193-204. DOI 10.1007/BF02759809 | MR 0469757 | Zbl 0369.02035

[5] J. Trlifaj, T. Kepka: Structure of T-rings. in Colloq. Math. Soc. Bolyai, 38. Radical theory, 633-655, North-Holland, Amsterdam, 1985. MR 0899130 | Zbl 0588.16021

[6] J. Trlifaj: Ext and von Neumann regular rings. Czech. Math. J. 35 (1985), 324-332. MR 0787134 | Zbl 0577.16007

[7] J. Trlifaj: Whitehead property of modules. Czech. Math. J. 36 (1986), 467-475. MR 0847773 | Zbl 0616.16009