Tcha-káuk-o-ko-máugh, Great Chief, a Boy by George Catlin, 1831
To find a home page for a specific tribal nation, look through the list below, check out this page of links, or try Google.
Winnebago Reformed Church, Winnebago, NE
Winnebago Powwow, 2006.
There are so many great websites for historical research,
with both primary and secondary sources.
While this is not a complete list, it's a good start: