Zainalov, B. R. “First Nontrivial Group of Homologies of Simplicial Schemes of Unimodular Frames over the Dedekind Ring”. Ukrains’kyi Matematychnyi Zhurnal, vol. 70, no. 9, Sept. 2018, pp. 1231-48, https://umj.imath.kiev.ua/index.php/umj/article/view/1630.