“The Effectiveness of Group Counseling Using the Behavior Contract Technique in Improving Vocational High School Students’ Discipline” (2026) Hambaruan: Jurnal Psikologi, Konseling, dan Pendidikan Anak Usia Dini, 1(1), hlm. 16–26. Tersedia pada: https://abecen.com/index.php/Hambaruan/article/view/12 (Diakses: 3 Juni 2026).