Orison Swett Marden (1896). “Pushing to the Front: Or Success Under Difficulties, a Book of Inspiration and Encouragement to All who are Struggling for Self-elevation Along the Paths of Knowledge and of Duty”
Orison Swett Marden (2015). “An Iron Will, He Can Who Thinks He Can & Pushing To The Front (Wisdom & Empowerment Series): How to Achieve Self-Reliance Which Leads to Vigorous Self-Faith, Personal Growth & Success”, p.389, e-artnow