Nordfriesland map of Johannes Mejer around 1240 (before the storm surge 1362). The red lines indicate the coastline at the time of the report template.
<bdi><a href="https://www.wikidata.org/wiki/Q91086" class="extiw" title="d:Q91086"><span title="German mathematician and cartographer">Johannes Mejer</span></a>
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"Nordfriesland früher und heute", Bogdan Gisevius, Berlin W.