"Michigan, Marriages, 1868-1925," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/N3V1-G64 : accessed 23 December 2014), Cornelius J. Heyboer and Nellie Bouwkamp, 21 Apr 1909; citing Grand Rapids, Kent, Michigan, v 3 p 30 rn 3838, Department of Vital Records, Lansing; FHL microfilm 2,342,685.