Janchaiyaphoom, Hathainuch, and Suwimon Theakthum. 2023. “DEVELOPMENT OF THE NATURAL RUBBER SPONGE MIXED PASSION FRUIT PEEL CHARCOAL POWDER TO PRODUCE CUSHIONS USING DESIGN OF EXPERIMENT”. PSRU Journal of Science and Technology 8 (3). Phitsanulok, Thailand:69-81. https://ph01.tci-thaijo.org/index.php/Scipsru/article/view/253525.