Manzoor, Zafar, and Humna Ahsan. “Definitions and Estimation Models of Shadow Economy: A Systemic Literature Review”. CARC Research in Social Sciences 3, no. 2 (June 30, 2024): 233–240. Accessed June 20, 2025. https://journals.carc.com.pk/index.php/CRISS/article/view/135.