Sirait, Bilter A., Agnes Imelda Manurung, and R. Sabrina. 2021. “Pengaruh Perlakuan EM4 Dan NPK Terhadap Kandungan Hara NPK Daun Kelapa Sawit Di Pre-Nursery”. Jurnal Penelitian Bidang Ilmu Pertanian 19 (2):20-23. https://lldikti1.kemdikbud.go.id/jurnal/index.php/bip/article/view/97.