"United States World War I Draft Registration Cards, 1917-1918," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:K6FS-D89 : accessed 8 February 2016), Otto Gustava Albert Hackbarth, 1917-1918; citing Cincinnati City no 2, Ohio, United States, NARA microfilm publication M1509 (Washington D.C.: National Archives and Records Administration, n.d.); FHL microfilm 1,819,800.