"U.S. Naturalization Records - Original Documents, 1795-1972 (World Archives Project)", database and images, Ancestry.com (http://search.ancestry.com/search/db.aspx?dbid=1193 : accessed 1 Sep 2012), entry for Johan Otto Hallin declaration of intention (1911), Eastern District of Washington, file no 3878; citing NARA Microfilm series M1541 roll 13.