GandhyA., Harianto, NurmalinaR., and Suharno. “The Efficiency of The Spot Market And Crude Palm Oil (CPO) Commodity Futures Market Before and During The Covid-19 Pandemic in Indonesia”. Jurnal Manajemen & Agribisnis, Vol. 19, no. 1, Mar. 2022, p. 139, doi:10.17358/jma.19.1.139.