DENBEL, Dejene Girma. Students Difficulties of Solving Inequalities in Calculus. American Scientific Research Journal for Engineering, Technology, and Sciences, Jordan, v. 5, n. 1, p. 57–62, 2013. Disponível em: https://asrjetsjournal.org/American_Scientific_Journal/article/view/761. Acesso em: 12 sep. 2025.