Trakanpruk, W. ., and Y. . Rodthong. “Production of Sponge Rubber for Monolayer Rubber Stamp Using Salt Leaching Method”. Journal of Metals, Materials and Minerals, vol. 18, no. 2, Apr. 2017, https://jmmm.material.chula.ac.th/index.php/jmmm/article/view/308.