When copying data from this family tree, please include a reference to the origin: J.H.Douma, "Family tree Douma", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-douma/I22508.php : accessed February 17, 2026), "Sascker Ritsckes (Zacharias) Jelmera (Donia, Heringa, Cammingha, Jelmers) (1407-1448)".
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