Khasanah, A., A. Sutoyo, and E. Nusantoro. “Meningkatkan Motivasi Belajar Siswa Underachiever Melalui Layanan Bimbingan Kelompok”. Indonesian Journal of Guidance and Counseling: Theory and Application, Vol. 2, no. 3, Sept. 2013, doi:10.15294/ijgc.v2i3.3194.