Okpon, S. N., & Aduayi, E. A. (2014). Nitrogen Nutrition of White Yam (Dioscorea rotundata Poir) Grown in Two Selected Locations of Southwestern Nigeria. Obafemi Awolowo University.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Okpon, Stephen Nelson, و E. A. Aduayi. Nitrogen Nutrition of White Yam (Dioscorea Rotundata Poir) Grown in Two Selected Locations of Southwestern Nigeria. Obafemi Awolowo University, 2014.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)Okpon, Stephen Nelson, و E. A. Aduayi. Nitrogen Nutrition of White Yam (Dioscorea Rotundata Poir) Grown in Two Selected Locations of Southwestern Nigeria. Obafemi Awolowo University, 2014.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.