Wan, Lei, Mingce Long, Dongying Zhou, Liying Zhang, and Weimin Cai. 2012. “Preparation and Characterization of Freestanding Hierarchical Porous TiO2 Monolith Modified With Graphene Oxide”. Nano-Micro Letters 4 (2):90-97. https://doi.org/10.1007/BF03353698.