Henning H, Henning M. Origins of Dualism and Nondualism in the History of Religion and Spiritual Practice. Religions. 2022; 13(10):1004. https://doi.org/10.3390/rel13101004
Storm, Ingrid. “Halfway to Heaven: Four Types of Fuzzy Fidelity in Europe.” Journal for the Scientific Study of Religion 48, no. 4 (2009): 702–18. http://www.jstor.org/stable/40405664.
Cornelis Anthonie van Peursen, Antropologia filozoficzna. Zarys problematyki, Rozdział IV. Skrajny materializm: Feuerbach, Warszawa 1971, PAX, s. 56, na podstawie: J. J. Poortman, Ochêma. Geschiedenis en zin van het Hylisch Pluralisme (Het zg. Dualistisch Materialisme), Assen, 1954, passim.