Fadaee, M., and E. Bagherzadeh. “Evaluating the Effect of Humic Acid on the Yield of Three Varieties of Potato under Field Conditions”. Journal of Research in Biology, Vol. 7, no. 5, Aug. 2017, pp. 2316-20, https://ojs.jresearchbiology.com/index.php/jrb/article/view/450.