Aritonang, Salam N., and Sri Melia. “Utilization of Milk Processing by Product (Whey) As Based of Edible Film Making With Glycerol Adding As Plasticizer”. Pakistan Journal of Nutrition, vol. 13, no. 6, May 2014, pp. 327–330, https://doi.org/10.3923/pjn.2014.327.330.