R. I. M. . DAMANIK, C. . HANUM, and L. J. . SEMBIRING, “Response of various growth regulators and shade intensity to the growth of arabica coffee seedlings of Sigarar Utang variety”, Nusantara Biosci, vol. 15, no. 1, Apr. 2023, doi: 10.13057/nusbiosci/n150110.