References/ Références:
Bowen W.D., Sergeant D.E., and Øritsland T. 1983. Validation of age estimation in the harp seal, Phoca groenlandica, using dentinal annuli. Canadian Journal of Fisheries and Aquatic Sciences. 40:1430-41.
Campana, S. E. (2004). Photographic atlas of fish otoliths of the Northwest Atlantic Ocean (No. 133). NRC Research Press. 284 p.
Camphuysen, K. and P. Henderson. 2017. North Sea Fish and Their Remains. Pices Conservation Limited. 326 p. 
Fisher, H.D. 1954. Studies on reproduction in the harp seal. PhD dissertation. Dept. of Zoology, McGill University, Montreal, QC, Canada.
Frandsen, R.P. and Zumholz, K. 2004. Cephalopods in Greenland Waters – a field guide. Pinngortitaleriffik, Technical report no. 58. Greenland Institute of Natural Resources. 
Frie, A., Fagerheim, K.-A., Hammill, M.O., Kapel, F.O., Lockyer, C., Stenson, G.B., Rosing-Asvid, A., and Svetochev, V. 2011. Error patterns in age estimation of harp seals (Pagophilus groenlandicus): results from a transatlantic, image-based blind-reading experiment using known-age teeth. ICES Journal of Marine Science 68:1942-1953.
Härkönen, T., 1986. Guide to the otoliths of the bony fishes of the Northeast Atlantic. Hellerup, Denmark 256 p.
ICES. 1997. Guide to the identification of North Sea fish using Premaxillae and Vertebrae. ICES Cooperative Research report. Vol. 220, 235 pp. https://doi.org/10.17895/ices.pub.4627
Murie, D.J., and Lavigne, D.M. 1985. A technique for the recovery of otoliths from stomach contents of piscivorous pinnipeds. Journal of Wildlife Management. 49: 910-912.
Nozères, C. and M. Bérubé. 2003. Marine Species Identification Guide for the St. Lawrence. Maurice Lamontagne Institute, Fisheries and Oceans Canada.
Scott and Scott (1988) Atlantic Fishes of Canada. University of Toronto Press. 731 p.
Sjare, B., & Stenson, G. B. 2000. Recent estimates of reproductive rates for harp seals in the Northwest Atlantic. DFO Can. Sci. Advis. Sec. Res. Doc. 2000/077, 13 p. 
Squires, H.J., 1990. Decapod Crustacea of the Atlantic Coast of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences. 221: 532 p.