“The Effectiveness of Group Counseling Using the Behavior Contract Technique in Improving Vocational High School Students’ Discipline”. Hambaruan: Jurnal Psikologi, Konseling, dan Pendidikan Anak Usia Dini 1, no. 1 (Juni 1, 2026): 16–26. Diakses Juni 3, 2026. https://abecen.com/index.php/Hambaruan/article/view/12.