Daniel Ganda Putra Sihombing, David Togi Hutahaean, Yanti kristina Sinaga, Tiarma Intan Marpaung, Anita Sitanggang. The Effect Of Reinforcement On Writing Skill At Eleventh Grade Students In SMK Negeri 1 Pematang Siantar . JIPSI [Internet]. 2023 Oct. 31 [cited 2026 Apr. 17];2(3):381-9. Available from: https://putrapublisher.org/ojs/index.php/jipsi/article/view/447