H. T. M. Nguyễn, D. Hoang, and T. C. Phạm, “Study of flame retardancy, thermal and physical properties of rigid polyurethane foam based on recycled poly(ethylene terephthalate) using non-halogen flame retardant”, Science & Technology Development Journal: Natural Sciences, vol. 5, no. 2, pp. 1189-1197, Apr. 2021.