^Ferrer, Jorge N. (2002). Revisioning transpersonal theory: a participatory vision of human spirituality. State Univ. of New York Press. p. 76. ISBN978-0-7914-5167-0.
Further reading
Malinova, Mariana (26 May 2020). "Al-Fārābī and His Concept of Epistemological Hierarchy". Knowledge and Education in Classical Islam: Religious Learning between Continuity and Change (2 vols): 186–199. doi:10.1163/9789004413214_010.