Sinaga, Yolanda, et al. “Improving Students Vocabulary Mastery by Using Ice Breaker Activities to the First Graders of SMP HKBP Sidorame”. Innovative: Journal Of Social Science Research, vol. 3, no. 2, June 2023, pp. 8237-42, http://j-innovative.org/index.php/Innovative/article/view/1113.