Cornelius Koopman, Jul 1840 (Netherlands)
Minnie Koopman, Nov 1848 (Netherlands)
Years Married: 33 [1867]
John Koopman, Feb 1884 (Michigan)
"United States Census, 1900," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/MSMR-PY1 : accessed 26 Nov 2013), Cornelius Koopman, ED 51 Precinct 3 Grand Rapids city Ward 2, Kent, Michigan, United States; citing sheet 7A, family 131, NARA microfilm publication T623, FHL microfilm 1240721.