Here is the opinion in Democratic National Committee v. Hobbs. A powerful history of the State’s suppression of Native voting begins on page 54 of Judge Fletcher’s majority opinion. The work of Patty Ferguson-Bohnee is cited repeatedly on this point.
Here are the materials in Spirit Lake Tribe v. Jaeger (D. N.D.):
Here is “Backlash over North Dakota voter ID law could rally Native Americans.”