F. Rahayu, R. T. Andri Agus, and S. Suparmadi, “APPLICATION OF CERTAINTY FACTOR METHOD FOR ANALYSIS OF PESTS AND DISEASES OF SPINACH PLANTS AT THE AGRICULTURAL OFFICE OF ASAHAN DISTRICT”, J. Tek. Inform. (JUTIF), vol. 3, no. 4, pp. 1061-1068, Aug. 2022.