People Quotes - Page 768
Ken Wilber (2001). “Sex, Ecology, Spirituality: The Spirit of Evolution, Second Edition”, p.541, Shambhala Publications
Katie J. Davis, Beth Clark (2012). “Kisses from Katie: A Story of Relentless Love and Redemption”, p.128, Simon and Schuster
"Observations". Book by Katharine Whitehorn, 1970.