Part III, Proposition 56. Spinoza, Benedictus de (2001) [1677]. Ethics. Trans. by W.H. White and A.H. Stirling. London: Wordsworth Editions. p. 141. ISBN978-1-84022-119-0. Retrieved 27 November 2011.
"In truth I cannot recognize any difference between human appetite and desire". Spinoza, Benedictus de (2001) [1677]. Ethics [heading= Affect. Trans. by W.H. White and A.H. Stirling. London: Wordsworth Editions. p. 146. ISBN978-1-84022-119-0. Retrieved 27 November 2011.
Existendi vis or power of existence. Spinoza, Benedictus de (2001) [1677]. Ethics. Trans. by W.H. White and A.H. Stirling. London: Wordsworth Editions. p. 158. ISBN978-1-84022-119-0. Retrieved 27 November 2011.