Dinihari, Pancayani, et al. “Evaluation of Learning Cycle 4E-RE to Improve Chemistry Learning of Vocational High School Student”. Journal of Technical Education and Training, vol. 13, no. 2, Mar. 2021, pp. 108-14, https://penerbit.uthm.edu.my/ojs/index.php/JTET/article/view/7518.