Gynastiar, Khotib. “The Effect of Price and Promotion on Distributor Purchase Interest in ZA Plus Fertilizer PT Petrokimia Gresik”. International Management Conference and Progressive Papers, vol. 2, no. 1, Nov. 2024, pp. 54-62, https://proceeding.unesa.ac.id/index.php/immersive/article/view/4077.