Yetri, Y. “Potential Activated Carbon of Theobroma Cacao L. Shell for Pool Water Purification in Politeknik Negeri Padang”. Jurnal Riset Teknologi Pencegahan Pencemaran Industri, vol. 12, no. 1, May 2021, pp. 32-38, doi:10.21771/jrtppi.2021.v12.no1.p32-38.