Supriyono, Supriyono, et al. “Synthesis and Characterization of Cassava Shell Based Biodegradable Plastic With Kitosan Addition”. Journal of Natural Sciences and Mathematics Research, vol. 3, no. 1, Aug. 2017, pp. 198-02, https://journal.walisongo.ac.id/index.php/JNSMR/article/view/1694.