Yuwanto, Listyo, and Gunadi Atmadji. “Pengembangan Fortitude Questionnaire Versi Indonesia”. Jurnal Ilmiah Psikologi MIND SET 8, no. 01 (May 24, 2019): 31 - 36. Accessed December 20, 2024. https://journal.univpancasila.ac.id/index.php/mindset/article/view/321.