HASHEM, A.R. “Effect of Cobalt on the Growth of Pear Fruit Rot Pathogens, Aspergillus Candidus and A. Clavatus Isolated from Saudi Arabia”. Indian Phytopathology, vol. 49, no. 1, Jan. 2002, pp. 72-76, https://epubs.icar.org.in/index.php/IPPJ/article/view/20036.