"Michigan, Death Certificates, 1921-1952," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/KF73-XHP : accessed 27 February 2015), Gerrit Vander Werff, 10 Feb 1940; citing Zeeland, Ottawa, Michigan, United States, Division for Vital Records and Health Statistics, Lansing; FHL microfilm 1,973,076.