The objective of this paper is to study the question of when modules have ADS^-preenvelopes and covers. It is proved that every ADS^ module over a ring R is projective if and only if every right R-module has an ADS^- (pre) envelope (an ADS^- (pre) cover). We also introduce a generalization of ADS^ modules in terms of their invariance under certain automorphisms of their envelopes.
Dung Banh Duc (2026) studied this question.