Morgan, Gerald (1979). "The Significance of the Pentangle Symbolism in "Sir Gawain and the Green Knight"". The Modern Language Review. 74 (4): 769–790. doi:10.2307/3728227. JSTOR3728227.
Morgan, Gerald (1979). "The Significance of the Pentangle Symbolism in "Sir Gawain and the Green Knight"". The Modern Language Review. 74 (4): 769–790. doi:10.2307/3728227. JSTOR3728227.
Lévi, Éliphas (1999) [1854 (first published)]. Transcendental Magic, its Doctrine and Ritual[Dogme et rituel de la haute magie]. York Beach, Maine: Weiser. OCLC263626874.