1. Barrett, Timothy H. 1992. Li Ao: Buddhist, Taoist, or Neo-Confucian? Oxford: Oxford University Press.
2. Barrett, Timothy H. 1994. "The Emergence of the Taoist Papacy in the T'ang Dynasty." Asia Major, 3rd ser. 7: 89–106.
3. Barrett, Timothy H. 1996. Taoism under the T'ang. London: Wellsweep Press.