haffner in north dakota

I am looking for any information on my great + grandparents. They are John and Elizabeth Haffner. They were from Germany. They had 3 children- Adolph, Mike, Matt who were born in Minnesota,in 1850's. They move to Richland county, North Dakota I found them in the 1880 census. Adolph died in richland county, North Dakota in the 1930's ?