Hoffmann, G., Kuijpers, A., & Thiede, J. (1999). "Poseidon" cruise No. 243 Reykjavik - Greenland - Reykjavik 24 August - 11 September 1998: Climate change and the Viking-age fjord environment of the Eastern Settlement, sw Greenland. Alfred-Wegener-Institut für Polar- und Meeresforschung.
Cytowanie według stylu Chicago (wyd. 17)Hoffmann, Gerd, Antoon Kuijpers, i Jörn Thiede. "Poseidon" Cruise No. 243 Reykjavik - Greenland - Reykjavik 24 August - 11 September 1998: Climate Change and the Viking-age Fjord Environment of the Eastern Settlement, Sw Greenland. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 1999.
Cytowanie według stylu MLA (wyd. 9)Hoffmann, Gerd, et al. "Poseidon" Cruise No. 243 Reykjavik - Greenland - Reykjavik 24 August - 11 September 1998: Climate Change and the Viking-age Fjord Environment of the Eastern Settlement, Sw Greenland. Alfred-Wegener-Institut für Polar- und Meeresforschung, 1999.