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.
jstor.org
Gurewich, Vladimir, "Rubens and the Wound in Christ's Side. A Postscript", Journal of the Warburg and Courtauld Institutes, Vol. 26, No. 3/4 (1963), p. 358, The Warburg Institute, JSTOR
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.