we are looking for lost oil lease information for the Senn family in North Dakota under anderson oil company?

It was willed to Julia Ann Strobl and then was supposed to go to her children, Mike, Wilhelm and Mildred. Mike Strobl, Julia's husband was receiving a check for the children in the 1970's and 80's when all funds stopped and paper work was lost at his death. Please help us to find out what happened to them.