G. Otobo, Endurance Fegor Isoje, and Augustina Ufuoma Igbuku, “Hazardous Nature of Native Chalk (Calabash chalk)”, IJSBAR, vol. 71, no. 1, pp. 31–36, Oct. 2023, Accessed: Nov. 03, 2025. [Online]. Available: https://www.gssrr.org/JournalOfBasicAndApplied/article/view/16177