"HECKMAN MODEL FOR IDENTIFYING THE PROBABILITY OF ADOPTION OF IMPROVED VARIETIES OF SORGHUM, MILLET, GROUNDNUT AND SESAME IN NORTH KORDOFAN STATE, SUDAN". University of Kordofan Journal of Natural Resources & Enviromental Studies 5, no. 01 (ديسمبر 21, 2025): 26–43. تاريخ الوصول يناير 1, 2026. https://journals.kordofan.edu.sd/jr/index.php/ukjnres/article/view/12.