<https://www.csarmento.uminho.pt/site/api/mapping_markers/375>
<http://omeka.org/s/vocabs/module/mapping#lng>
"-2.363481813402609E1"^^<http://www.w3.org/2001/XMLSchema#double>
<https://www.csarmento.uminho.pt/site/s/postal-ilustrado/item/153766>