Qin, Yuancheng, et al. “Preparation of Polyhedral Oligosilsesquioxane-Based Organic-Inorganic Hybrid Porous Nanocomposite by Freeze-Drying Conditions”. Asian Journal of Chemistry, vol. 25, no. 3, Oct. 2012, pp. 1229-32, doi:10.14233/ajchem.2013.12609.