Erwiyono, R., A. Sucahyo, S. ., and S. Winarso. “Effectiveness of Foliar Application of Potassium on Flowering and Fruiting of Cocoa”. Pelita Perkebunan (a Coffee and Cocoa Research Journal), Vol. 22, no. 1, May 2006, doi:10.22302/iccri.jur.pelitaperkebunan.v22i1.26.