Let $R\rightarrow S$ be a ring homomorphism. We analyze the relationship between the precovers (preenvelopes) in the category of right $R$-modules and the counterparts in the category of right $S$-modules. Some applications are also given.
"Precovers and preenvelopes under change of rings." Rocky Mountain J. Math. 45 (5) 1527 - 1554, 2015. https://doi.org/10.1216/RMJ-2015-45-5-1527