The Minnesota Historical Society has created excellent descriptions of their collections, and even digitized entire collections for online use.
This is just a sampling of what is available at the Society!
They Chose Minnesota
by
June D. Holmquist (Editor)
The Nonpartisan League 1915-1922: An Annotated Bibliogrpahy
by
Patrick K. Coleman and Charles R. Lamb
To Be the Main Leaders of Our People: A History of Minnesota Ojibwe Politics, 1825-1898
by
Rebecca Kugel
Archaeology of Minnesota : the prehistory of the upper Mississippi river region
by
Gibbon, Guy E
Shaping the North Star State : a history of Minnesota's boundaries
by
Lass, William E.
Somalis in the Twin Cities and Columbus: Immigrant Incorporation in New Destinations
by
Chambers, Stefanie
Newspapers are a rich source of information on Minnesota's history. These online databases are open-source and full-text.