KhmelnitskiiN. A. “On the Chain Equivalence of Projective Chain Complexes”. Ukrains’kyi Matematychnyi Zhurnal 64, no. 6 (June 25, 2012): 826-835. Accessed November 23, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2620.