Darma, I. K., . I. G. M. Karma, and I. M. A. Santiana. “Practicality and Effectiveness of Digital Mathematics Teaching Materials in Improving the Problem-Solving Ability for Polytechnic Students”. International Research Journal of Engineering, IT & Scientific Research, vol. 7, no. 6, Oct. 2021, pp. 203-1, doi:10.21744/irjeis.v7n6.1935.