A. M. Al-Doori, S. “Effect of Different Levels and Timing of Zinc Foliar Application on Growth, Yield and Quality of Sunflower Genotypes (Helianthus Annuus L., Compositae”. College of Basic Education Research Journal, vol. 13, no. 1, June 2014, pp. 907-22, https://jeh.uomosul.edu.iq/index.php/berj/article/view/39527.