Büyükasik, Engin, and Christian Lomp. “Rings Whose Modules Are Weakly Supplemented Are Perfect. Applications to Certain Ring Extensions”. Mathematica Scandinavica 105, no. 1 (September 1, 2009): 25–30. Accessed July 24, 2026. https://journals.msp.org/mscand/article/view/593.