Marriage Dedrik Maanum to Ranghild Fossebraten

Seeking info on grandparents. Have some info on my grandfather Dedrik A Maanum in Montana, North Dakota, Minnesota (believe born USA with parents born Norway). But cannot find any record of marriage to my grandmother Ranghild Fossebraten (born in Norway), known in USA after marriage as Rose Maanum. Rose died in about 1924 in Minneapolis. My mother Annette Juline Maanum Cina was their eldest child, and she was born in Napoleon ND on 6/29/1908. Any help/info appreciated.