Off-Farm Incomes Share and Farm Investment in North-Central, Nigeria: The Heckman Selection Model Approach. Global Journal of Human-Social Science, [S. l.], v. 15, n. E3, p. 1–7, 2015. Disponível em: https://socialscienceresearch.org/index.php/GJHSS/article/view/1415. Acesso em: 19 feb. 2026.