Donald Ricky, Native Peoples A to Z: A Reference Guide to Native Peoples of the Western Hemisphere, Volume 8, Native American Book Publishers, , 3810 p. (ISBN978-1-878592-73-6, lire en ligne).
James R. Glenn, « De Lancey W. Gill: Photographer for the Bureau of American Ethnology », History of Photography, vol. 7, no 1, , p. 7-22 (lire en ligne, consulté le ).
loc.gov
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« Christian Rites for Big Chief, Impressive Services Held at Washington for Chief Hollow Horn Bear, After Ceremonies Body was Taken west to its Last Resting Place », The Bismarck Tribune, (lire en ligne, consulté le ).