As’ad, S., P. Sudira, and . A. Hasriani. “The Affecting Factors Difficulty in Learning: Case in Vocational School Students”. The International Journal of Social Sciences World (TIJOSSW), vol. 3, no. 1, Apr. 2021, pp. 155-64, https://www.growingscholar.org/journal/index.php/TIJOSSW/article/view/105.