Barat Zadeh, Sara, Saki Nejad2*, Tayeb, Babaei Nejad, Teymour. “Effect of potassium nano-chelate and ascorbic acid on grain yield and some qualitative characteristics of cowpea (Vigna unguiculata L., Kamran cultivar).” Journal of Plant production Sciences, vol. 9, no. 2, 2019, pp. 149-160.