Petrography of stone used for sculpture from the Buddhist cave temples of Xiangtangshan dating to the Northern Qi dynastyv. 293–114
Douglas, Janet G. and Haynes, John T. 2014. "Petrography of stone used for sculpture from the Buddhist cave temples of Xiangtangshan dating to the Northern Qi dynasty." Metropolitan Museum Studies in Art, Science, and Technology, 2 93–114.