"Michigan, Death Certificates, 1921-1952," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:KF3N-RC8 : accessed 13 July 2015), Cornelia (Nellie) Ritzema, 29 Jan 1937; citing Wyoming, Kent, Michigan, United States, Division for Vital Records and Health Statistics, Lansing; FHL microfilm 1,972,813.