Searching for half brother

Searching for my half brother - We would have the same mother but different father. Adoptee was given up at birth. Born in Duluth, MN St. Louis County Welfare Department is the county that facilitated the adoption, and the adoption was finalized in St. Louis County, Minnesota Birth Mother's Name: Susan Amy Carlson Birth Mother's Date of Birth: 04/10/1954 Estimated Date of Birth of Adoptee: Between 4/10/1968 and 4/10/1969