J. Umaru, E. P. Bako, and Z. Y. Lawal, “Livelihood and Income Diversification among Rural Households in Kaduna State, Nigeria: Evidence from Simpson’s Diversity Index ”, Kaduna J. Geogr., vol. 8, no. 1, pp. 703–714, Oct. 2026, doi: 10.47514/kjg.2026.08.01.067.