Orison Swett Marden (2015). “ORISON SWETT MARDEN Premium Collection - Wisdom & Empowerment Series (18 Books in One Volume): Steps to Success and Power, How to Get What You Want, An Iron Will, Be Good to Yourself, Every Man A King, Keeping Fit, Prosperity – How to Attract It, Stepping-Stones To Fame And Fortune...”, p.2404, e-artnow
Dr. Robert C. Worstell, Dorothea Brande, Claude M. Bristol, Earl Nightingale, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS01”, p.10, Lulu.com