“Annual Fecal Glucocorticoid Metabolite Concentrations in Pregnant and Pseudopregnant Polar Bears (Ursus Maritimus) in North American Zoos”. Journal of Zoo and Aquarium Research, vol. 6, no. 1, Jan. 2018, pp. 6-11, https://doi.org/10.19227/jzar.v6i1.259.