Heath, Thomas L. (1956). The Thirteen Books of Euclid's Elements. Vol. 2 (Books 3–9) (2nd ed.). Dover. p. 61. ISBN0486600890. Originally published by Cambridge University Press. 1st edition 1908, 2nd edition 1926.
Sidoli, Nathan (2018). "Greek mathematics"(PDF). In Jones, A.; Taub, L. (eds.). The Cambridge History of Science: Vol. 1, Ancient Science. Cambridge University Press. pp. 345–373.