Zhang, Zhigang, Tianzhu Zhang, Zhenling Ji, Xuefeng Zhou, and Ning Gu. 2011. “Direct Graft Polymerization of L-Lactic Acid onto Oxidatively Functionalized Polypropylene Flakes”. Asian Journal of Chemistry 24 (4):1495-98. https://asianpubs.org/index.php/ajchem/article/view/8840.