Rabbi Shlomo Wolbe, Alei Shur, Volume 1. Bais Hamussar, 1968, p. 141.

Deborah L. Black. «Avicenna on self-awareness and knowing that one knows,» in S. Rahman et al. (eds.), The Unity of Science in the Arabic Tradition. Springer, 2008, pp. 63–87, http://individual.utoronto.ca/dlblack/articles/blackselfknrev.pdf.