[1] Cohn P M. On the free product of asscociative rings. Math Z, 1959, 71: 380–398

[2] Fieldhouse D J. Pure Theories. Math Ann, 1969, 184: 1–18

[3] Maddox B H. Absolutely pure modules. Proc Amer Math Soc, 1967, 18: 155–158

[4] Stenstr¨om B. Coherent rings and FP-injective modules. J London Math Soc, 1970, 2(2): 323–329

[5] Cheng F C, Tang J Y, Huang Z Y, et al. -coherent rings and FGT-injective dimnsion. Southeast Asian Bull Math, 1995, 19 (3): 105–112

[6] Enochs E E, Jenda O M G. Copure injective resolutions, flat resolvents and dimensions. Comment Math Univ Carolin, 1993, 34(2): 203–211

[7] Azumaya G, Facchini A. Rings of pure global dimension zero and Mittag-Leffler modules. J Pure Appl Algebra, 1989, 62: 109–122

[8] Anderson F W, Fuller K R. Rings and Categories of Modules. New York: Springer-Verlag, 1974

[9] Enochs E E, Jenda O M G. Relative Homological Algebra//de Gruyter Exposition in Mathematics, 30. Berlin: Walter de Gruyter & Co, 2000

[10] Rotman J J. An Introduction to Homological Algebra. New York: Academic Press, 1979

[11] Colby R R. Rings which have flat injective modules. J Algebra, 1975, 35: 239–252

[12] G¨obel R, Trlifaj J. Approximations and Endomorphism Algebras of Modules//de Gruyter Exposition in Mathematics, 41. Berlin: Walter de Gruyter & Co, 2006: 29–116

[13] Salce L. Classi di gruppi abeliani chiuse rispetto alle immagini omomorfe ed ai limit proiettivi. Rend Sem Mat Univ Padova, 1973, 49: 1–7

[14] Puninski G, Rothmaler P. When every finitely generated flat module is projective? J Algebra, 2004, 277: 542–558