AL-Kaaby , M. “Effect of Urea and Humic Acid Fertilization on Some chemical/Physical Properties and Yield of Cow Pea Vigna Unguiculata (L.) Walp”. University of Thi-Qar Journal of Science, Vol. 3, no. 2, June 2019, pp. 82-88, https://www.jsci.utq.edu.iq/index.php/main/article/view/503.