A. R. Hakim, R. . Tutrianto, and M. D. A. . Permana, “Supervision of the Riau Province Plantation Service in Determining the Purchase Price of Fresh Fruit Bunches (FFB) in Siak Regency”, Pasundan.Soc.Scie.Dev, vol. 6, no. 1, pp. 84–92, Oct. 2025.