Thinking Quotes - Page 718
Florence Nightingale, Michael D. Calabria, Janet A. Macrae (1994). “Suggestions for Thought by Florence Nightingale: Selections and Commentaries”, p.99, University of Pennsylvania Press
"The Book of Disquiet". Book by Fernando Pessoa, p.173, 1982.
Ernie Harwell (2004). “Life after baseball”
Ernest Holmes (2012). “The Science of Mind Collection”, p.203, Penguin
Erin Morgenstern (2016). “The Night Circus”, p.269, Random House