Bibliographical sources mentioned in this text:
Agricola, Rodolphus 81.5
Cranzius, Albertus : Saxonia 81.9
Frisius, Gemma 81.5
Guicciardini, Ludovico : Description of the Low Countries 81.9
Hopper, Joachim 81.6, also mentioned in the inset map of ancient Friesland as its maker, Ort81
Kempius, Cornelius 81.9
Leo, Sibrandus is mentioned in the cartouche of this map as its maker, Ort81
Leon, Ælsius Eduardus Frisius 81.9
Mela, Pomponius 81.8
Olivar(i)us, Petrus : commenting on Pomponius Mela 81.8
Suffridus, Petrus 81.9
Verrutius, Hieronymus 81.9