Garde , E., Heide-Jørgensen , M. P., Ditlevsen , S., & Hansen , S. H. (2012). Aspartic acid racemization rate in narwhal (<em>Monodon monoceros</em&gt;) eye lens nuclei estimated by counting of growth layers in tusks. Polar Research, 31. https://doi.org/10.3402/polar.v31i0.15865