Dr. Robert C. Worstell, Dorothea Brande, Claude M. Bristol, Earl Nightingale, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS01”, p.154, Lulu.com
Jack Canfield, Mark Victor Hansen, Amy Newmark (2011). “Chicken Soup for the Soul: Preteens Talk: Inspiration and Support for Preteens from Kids Just Like Them”, p.349, Simon and Schuster