Nilssen, K. T., N.-E. Skavberg, M. Poltermann, T. Haug, T. Härkönen, and G. Henriksen. “Status of Harbour Seals (<i>Phoca vitulina</I>) in Mainland Norway”. NAMMCO Scientific Publications, vol. 8, Sept. 2010, pp. 61-69, doi:10.7557/3.2672.