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For any form of publication, please include the link to this page and give GRID-Arendal and the cartographer/designer credit (in this case Riccardo Pravettoni, UNEP/GRID-Arendal)
personal communication with Dr. Peter Prokosch, GRID-Arendal; Piersma, T., Davidson, N., The Migration of Knots, WSG Bulletin 64, 1992