"United States World War I Draft Registration Cards, 1917-1918," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/K87Y-785 : accessed 09 Oct 2013), Arthur Frederick Luderus, 1917-1918; citing St. Paul City no 3, Minnesota, United States, NARA microfilm publication M1509, (Washington D.C.: National Archives and Records Administration, n.d); FHL microfilm 1675894.