Pungwiwat, N., T. Deethayat, N. Duongbia, W. Kamopas, and T. Kiatsiriroat. “Use of copper metal balls as internal heat distributor in fixed-bed pyrolyzer of spent coffee grounds for biochar production”. Agriculture and Natural Resources, vol. 57, no. 4, Aug. 2023, pp. 579-, https://li01.tci-thaijo.org/index.php/anres/article/view/260447.