SQUID-based magnetic prospection in interdisciplinary case studies at possible early and high medieval harbour sites in Germany - Schneider, Michael; Linzen, Sven P.; Schiffler, Markus; Wunschel, Andreas; Hein, Michael; Roettig, Christopher-Bastian; Dunkel, Stefan; Stolz, Ronny; Ettel, Peter; Meyer, Hans-Georg; Baumgarten, Daniel (2015)