Margaret Brock Hanson was a rancher near Kaycee, Wyoming who later in life wrote on the history of Wyoming, using for material the collections and papers of her father, J. Elmer Brock. She published "Powder River Country: the Papers of J. Elmer Brock" in 1981 and "Frank Grouard, Army Scout: True Adventures in the Early West" in 1983. She subsequently edited several other books in the 1980s.
From the description of Margaret Brock Hanson papers, 1884-1981. (University of Wyoming, American Heritage Center). WorldCat record id: 64675211