Timmermann, H. R., M. W. Lankester, and A. B. Bubenik. “MORPHOLOGY OF THE BELL IN RELATION TO SEX AND AGE OF MOOSE (ALCES ALCES)”. Alces: A Journal Devoted to the Biology and Management of Moose, vol. 21, Jan. 1985, pp. 419-46, https://www.alcesjournal.org/index.php/alces/article/view/1423.