Peter Dronke (ed). A History of Twelfth-Century Western Philosophy. Cambridge University Press. 1988.
Frederick Denison Maurice. Moral and Metaphysical Philosophy. Macmillan and Co. London. 1873. Volume 1 (Ancient philosophy and the first to the thirteenth centuries). Chapter 4 ("Twelfth Century"). Page 534 et seq.
^Ancient philosophy and the first to the thirteenth centuries. v. 2. 14 th century to the French revolution, with a glimpse into the 19 th century. Macmillan. 1873. p. 534. Retrieved 28 August 2018.