___

• Amini, A., Amini, B., Ershad, M. and Sharif, H., On generalized perfect rings, Comm. Algebra (2007), 35(3), 953--963.
• Amini, A., Ershad, M. and Sharif, H., Rings over which flat covers of finitely generated modules are projective, Comm. Algebra (2008), 36(8), 2862--2871.
• Anderson, F. W. and Fuller, K. R., Rings and Categories of Modules, Graduate Texts in Mathematics, Springer-Verlag, New York, 1992.
• Atiyah, M. F. and Macdonald, I. G., Introduction to commutative algebra, Addison-Wesley Publishing Co., London, 1969. aydougdu2013rings : Aydoğdu, P., Rings over which every module has a flat δ-cover, Turkish J. Math. (2013), 37(1), 182--194.
• Bass, H., Finitistic dimension and a homological generalization of semi-primary rings, Trans. Amer. Math. Soc. (1960), 95, 466--488.
• Büyükaşık, E., Rings over which flat covers of simple modules are projective, J. Algebra Appl. (2012), 11(3), 1250046.
• Büyükaşık, E. and Lomp, C., When δ-semiperfect rings are semiperfect, Turkish J. Math. (2010), 34(3):317--324.
• Demirci, Y. M., On generalizations of semiperfect and perfect rings, Bull. Iranian Math. Soc. (2016), 42(6), 1441--1450.
• Enochs, E. E., Injective and flat covers, envelopes and resolvents, Israel J. Math. (1981), 39(3), 189--209.
• Kasch, F., Modules and rings, London Mathematical Society Monographs, Academic Press, Inc. [Harcourt Brace Jovanovich, Publishers], London-New York, 1982. Translated from German with a preface by D. A. R. Wallace.
• Lam, T. Y., Lectures on Modules and Rings, Graduate Texts in Mathematics, Springer, New York, 1999.
• Lomp, C., On semilocal modules and rings, Comm. Algebra (1999), 27(4), 1921--1935.
• Xu, J., Flat covers of modules, Lecture Notes in Mathematics, Springer-Verlag, Berlin, 1996.
• Zhou, Y., Generalizations of perfect, semiperfect, and semiregular rings, Algebra Colloq. (2000), 7(3), 305--318.