Muuttoranta, K., Øystein Holand, K. H. Røed, M. Tapio, M. Nieminen, and A. Mäki-Tanila. “Genetic and environmental effects affecting the variation in birth date and birth weight of reindeer calves”. Rangifer, vol. 33, no. 1, Nov. 2013, pp. 25-35, doi:10.7557/2.33.1.2598.