Nik Azmi, Nik Nur Ashirah, et al. “Chitosan Incorporated With Stingless Bee Propolis for Active Food Packaging Application”. Enhanced Knowledge in Sciences and Technology, vol. 1, no. 1, Feb. 2021, pp. 27-33, https://publisher.uthm.edu.my/periodicals/index.php/ekst/article/view/636.