1. Albanese, Catherine L. (2007). A Republic of Mind and Spirit: A Cultural History of American Metaphysical Religion, Yale University Press.
2. Alfred, Taiaiake (2005). Wasáse: Indigenous Pathways of Action and Freedom, University of Toronto Press.
3. Barnard, William G. (1997). Exploring Unseen Worlds: William James and the Philosophy of Mysticism, State University of New York Press.
4. Paradigms behind (and before) the modern concept of religion;Bell;History and Theory,2006
5. Tucker, Mary Eveyln (2009). The Sacred Universe, Columbia University Press.