Yang, Zi-Feng, et al. “Extraction and Separation of Polysaccharides from Radix Isatidis and Their Effects Towards Hemagglutinin Protein of Influenza Virus”. Asian Journal of Chemistry, vol. 27, no. 5, Feb. 2015, pp. 1615-20, doi:10.14233/ajchem.2015.17394.