Dr. Robert C. Worstell, Dorothea Brande, Eark Nightingale, Claude M. Bristol, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS02”, p.38, Lulu.com
Benjamin Disraeli, Edmund Gosse, Robert Arnot (1904). “The works of Benjamin Disraeli, earl of Beaconsfield: embracing novels, romances, plays, poems, biography, short stories and great speeches”
Dr. Robert C. Worstell, Dorothea Brande, Eark Nightingale, Claude M. Bristol, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS02”, p.6, Lulu.com