Robert Collier (2013). “The Secret of the Ages: The Secret Edition - Open Your Heart to the Real Power and Magic of Living Faith and Let the Heaven Be in You, Go Deep Inside Yourself and Back, Feel the Crazy and Divine Love and Live for Your Dreams”, p.44, Lulu Press, Inc
Benjamin Whichcote, Anthony Tuckney (1753). “Moral and religious aphorisms [collected by J. Jeffery from the papers of B. Whichcote]. Now re-publ., with additions, by S. Salter. To which are added, Eight letters: which passed between dr. Whichcote, and dr. Tuckney”, p.64