LOS ANGELES -- A new documentary about the life and work of “Little House on the Prairie” author Laura Ingalls Wilder puts her novels’ scattered racist references in historical context, the film’s producers said. Wilder’s work reflects the perspective of her family and attitudes in the late 1800s Midwest, the setting for the coming-of-age novels based on her childhood, said Mary McDonagh Murphy, director and producer of PBS’ “American Masters” biography.