When copying data from this family tree, please include a reference to the origin: B.J. Tissing, "Family tree Tissing", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-tissing/I2225.php : accessed February 6, 2026), "Bertrande van "Vrouwe van Schalkwijk, Heiress van Ijsselstein" Ijsselsteijn (± 1180-± 1230)".
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Request permission to copy data or at least inform the author, chances are that the author gives permission, often the contact also leads to more exchange of data.
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