The following publication contains information about John Sivertsen:
Article: "Pvt. Sivertsen's Horse: Victim of Little Big Horn" by Sandy Barnard •Artifacts recovered with the remains of a horse found along one of the retreat routes used by the Reno battalion suggest the animal was the mount of Pvt. John Sivertsen, Company M. • Greasy Grass, Annual of the Custer Battlefield Historical & Museum Association • Vol. 12 • May 1996.