When copying data from this family tree, please include a reference to the origin: Hans Middendorp, "Family Tree Family tree Kraster uit de Kalkwijk bij Sappemeer in Groningen", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-kraster/I12867.php : accessed January 17, 2026), "Jan Christoffer Kolk (1858-1916)".
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