Wayne W. Dyer (2009). “Your Erroneous Zones: Step-by-Step Advice for Escaping the Trap of Negative Thinking and Taking Control of Your Life”, p.32, Harper Collins
Thomas Watson (1794). “A Body of Practical Divinity Consisting of Above One Hundred and Seventy-six Sermons on the Shorter Catechism Composed by the Reverend Assembly of Divines at Westminster: With a Supplement of Some Sermons on Several Texts of Scripture Together with the Art of Divine Contentment ; to which is Added, Christ's Various Fulness”, p.233
Wayne W. Dyer (2009). “Your Erroneous Zones: Step-by-Step Advice for Escaping the Trap of Negative Thinking and Taking Control of Your Life”, p.32, Harper Collins