The following publications contain information about Marion Horn:
Article: "Little Bighorn: A battle remembered. A Date with History: Famous defeat intersected in Richmond natives' lives" by Dick Reynolds • Palladium-Item • Richmond, Indiana • 25 June 2001 • pp. 1A and 4A.
Article: "Out of Our Past: Richmond soldier was among the fallen at battle of Little Bighorn" • 1 July 2018.