^Smith H. (2000). Cleansing the Doors of Perception: The Religious Significance of Entheogenic Plants and Chemicals. New York, New York: Jeremy P. Tarcher/Putnam. p. 101. ISBN978-1-58542-034-6
^Richards WA. (2008). “The phenomenology and potential religious import of states of consciousness facilitated by psilocybin”. Archive for the Psychology of Religion30 (1): 189–199. doi:10.1163/157361208X317196.
Roberts, T. B. (editor) (2001). Psychoactive Sacramentals: Essays on Entheogens and Religion. San Francosco: Council on Spiritual Practices.
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Roberts, T. B. "Chemical Input—Religious Output: Entheogens." Chapter 10 in Where God and Science Meet: Vol. 3: The Psychology of Religious Experience Robert McNamara (editor)(2006). Westport, CT: Praeger/Greenwood.
Roberts, Thomas B. (October 22–24, 2004). “Entheogens — Sacramentals or Sacrilege?”. Northern Illinois University course syllabus. February 16, 2008時点のオリジナルよりアーカイブ。October 13, 2016閲覧。