Firmanto, Hendy, Yesi Kumalasari, and Zikil Muarrofah. “Determination of Cocoa Powder Quality Produced by Small-Medium Enterprise Using Six Sigma Analysis”. Pelita Perkebunan (a Coffee and Cocoa Research Journal) 37, no. 2 (August 1, 2021): 137-145. Accessed October 22, 2021. https://ccrjournal.com/index.php/ccrj/article/view/480.