BREW, Lewis; ACQUAH, Joseph; AMEGBEY, Newton. Extension of 2-Dimensional Planar Systems from Homological Algebra Perspective. American Scientific Research Journal for Engineering, Technology, and Sciences, Jordan, v. 38, n. 1, p. 112–117, 2017. Disponível em: https://www.asrjetsjournal.org/American_Scientific_Journal/article/view/3607. Acesso em: 18 sep. 2025.