A. J. Siahaan, Irsal, and B. Sitorus, “The Relationship between Climate and Productivity of Tea Plants (Camellia sinensis L.) in Bah-Butong Gardens PT. Perkebunan Nusantara IV, North Sumatra Province in 2005-2009.”, Petrop, vol. 11, no. 2, pp. 1-8, Aug. 2024.