An Indian Winter
This 1992 book by Russell Freedman recounts the 1833 expedition of German prince Maximilian of Wied and Swiss artist Karl Bodmer.
Knife River Indian Village
The National Park Service site for these Mandan and Hidatsa villages.
Mandan Indians
A brief report of Lewis & Clark's 1804 encounter with them, from PBS.
The Mandan Mystery
A lengthy examination of the controversy by Charles W. Moore, with particular emphasis on the Kensington Stone.
Prince Madog
This site recounts the legend of a Welsh prince who discovered America in about 1170, and whose descendants are the Mandan.